diff --git a/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp b/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
index 1e6baa5..365217a 100644
--- a/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
+++ b/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
@@ -374,7 +374,7 @@
     // Use 1 for count to indicate the word has inputted.
     const UnigramProperty unigramProperty(isBeginningOfSentence, isNotAWord,
             isBlacklisted, probability, HistoricalInfo(timestamp, 0 /* level */, 1 /* count */),
-            &shortcuts);
+            std::move(shortcuts));
     return dictionary->addUnigramEntry(CodePointArrayView(codePoints, codePointCount),
             &unigramProperty);
 }
@@ -434,10 +434,16 @@
     if (!dictionary) {
         return false;
     }
-    jsize wordLength = env->GetArrayLength(word);
-    int wordCodePoints[wordLength];
-    env->GetIntArrayRegion(word, 0, wordLength, wordCodePoints);
-    return false;
+    const PrevWordsInfo prevWordsInfo = JniDataUtils::constructPrevWordsInfo(env,
+            prevWordCodePointArrays, isBeginningOfSentenceArray,
+            env->GetArrayLength(prevWordCodePointArrays));
+    jsize codePointCount = env->GetArrayLength(word);
+    int wordCodePoints[codePointCount];
+    env->GetIntArrayRegion(word, 0, codePointCount, wordCodePoints);
+    const HistoricalInfo historicalInfo(timestamp, 0 /* level */, count);
+    return dictionary->updateCounter(&prevWordsInfo,
+            CodePointArrayView(wordCodePoints, codePointCount), isValidWord == JNI_TRUE,
+            historicalInfo);
 }
 
 // Returns how many language model params are processed.
@@ -509,7 +515,7 @@
         // Use 1 for count to indicate the word has inputted.
         const UnigramProperty unigramProperty(false /* isBeginningOfSentence */, isNotAWord,
                 isBlacklisted, unigramProbability,
-                HistoricalInfo(timestamp, 0 /* level */, 1 /* count */), &shortcuts);
+                HistoricalInfo(timestamp, 0 /* level */, 1 /* count */), std::move(shortcuts));
         dictionary->addUnigramEntry(CodePointArrayView(word1CodePoints, word1Length),
                 &unigramProperty);
         if (word0) {
diff --git a/native/jni/src/suggest/core/dictionary/dictionary.cpp b/native/jni/src/suggest/core/dictionary/dictionary.cpp
index c3f4229..8d3f8a9 100644
--- a/native/jni/src/suggest/core/dictionary/dictionary.cpp
+++ b/native/jni/src/suggest/core/dictionary/dictionary.cpp
@@ -155,6 +155,14 @@
     return mDictionaryStructureWithBufferPolicy->removeNgramEntry(prevWordsInfo, codePoints);
 }
 
+bool Dictionary::updateCounter(const PrevWordsInfo *const prevWordsInfo,
+        const CodePointArrayView codePoints, const bool isValidWord,
+        const HistoricalInfo historicalInfo) {
+    TimeKeeper::setCurrentTime();
+    return mDictionaryStructureWithBufferPolicy->updateCounter(prevWordsInfo, codePoints,
+            isValidWord, historicalInfo);
+}
+
 bool Dictionary::flush(const char *const filePath) {
     TimeKeeper::setCurrentTime();
     return mDictionaryStructureWithBufferPolicy->flush(filePath);
diff --git a/native/jni/src/suggest/core/dictionary/dictionary.h b/native/jni/src/suggest/core/dictionary/dictionary.h
index 09f8eac..a58dbfb 100644
--- a/native/jni/src/suggest/core/dictionary/dictionary.h
+++ b/native/jni/src/suggest/core/dictionary/dictionary.h
@@ -22,6 +22,7 @@
 #include "defines.h"
 #include "jni.h"
 #include "suggest/core/dictionary/ngram_listener.h"
+#include "suggest/core/dictionary/property/historical_info.h"
 #include "suggest/core/dictionary/property/word_property.h"
 #include "suggest/core/policy/dictionary_header_structure_policy.h"
 #include "suggest/core/policy/dictionary_structure_with_buffer_policy.h"
@@ -90,6 +91,10 @@
     bool removeNgramEntry(const PrevWordsInfo *const prevWordsInfo,
             const CodePointArrayView codePoints);
 
+    bool updateCounter(const PrevWordsInfo *const prevWordsInfo,
+            const CodePointArrayView codePoints, const bool isValidWord,
+            const HistoricalInfo historicalInfo);
+
     bool flush(const char *const filePath);
 
     bool flushWithGC(const char *const filePath);
diff --git a/native/jni/src/suggest/core/dictionary/property/ngram_property.h b/native/jni/src/suggest/core/dictionary/property/ngram_property.h
index 49f683b..dce4600 100644
--- a/native/jni/src/suggest/core/dictionary/property/ngram_property.h
+++ b/native/jni/src/suggest/core/dictionary/property/ngram_property.h
@@ -27,7 +27,7 @@
 class NgramProperty {
  public:
     NgramProperty(const std::vector<int> &&targetCodePoints, const int probability,
-            const HistoricalInfo &historicalInfo)
+            const HistoricalInfo historicalInfo)
             : mTargetCodePoints(std::move(targetCodePoints)), mProbability(probability),
               mHistoricalInfo(historicalInfo) {}
 
diff --git a/native/jni/src/suggest/core/dictionary/property/unigram_property.h b/native/jni/src/suggest/core/dictionary/property/unigram_property.h
index 4c61f96..d1f0ab4 100644
--- a/native/jni/src/suggest/core/dictionary/property/unigram_property.h
+++ b/native/jni/src/suggest/core/dictionary/property/unigram_property.h
@@ -54,11 +54,18 @@
               mProbability(NOT_A_PROBABILITY), mHistoricalInfo(), mShortcuts() {}
 
     UnigramProperty(const bool representsBeginningOfSentence, const bool isNotAWord,
-            const bool isBlacklisted, const int probability, const HistoricalInfo &historicalInfo,
-            const std::vector<ShortcutProperty> *const shortcuts)
+            const bool isBlacklisted, const int probability, const HistoricalInfo historicalInfo,
+            const std::vector<ShortcutProperty> &&shortcuts)
             : mRepresentsBeginningOfSentence(representsBeginningOfSentence),
               mIsNotAWord(isNotAWord), mIsBlacklisted(isBlacklisted), mProbability(probability),
-              mHistoricalInfo(historicalInfo), mShortcuts(*shortcuts) {}
+              mHistoricalInfo(historicalInfo), mShortcuts(std::move(shortcuts)) {}
+
+    // Without shortcuts.
+    UnigramProperty(const bool representsBeginningOfSentence, const bool isNotAWord,
+            const bool isBlacklisted, const int probability, const HistoricalInfo historicalInfo)
+            : mRepresentsBeginningOfSentence(representsBeginningOfSentence),
+              mIsNotAWord(isNotAWord), mIsBlacklisted(isBlacklisted), mProbability(probability),
+              mHistoricalInfo(historicalInfo), mShortcuts() {}
 
     bool representsBeginningOfSentence() const {
         return mRepresentsBeginningOfSentence;
diff --git a/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h b/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
index f4b9798..6624b79 100644
--- a/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
+++ b/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
@@ -21,6 +21,7 @@
 
 #include "defines.h"
 #include "suggest/core/dictionary/binary_dictionary_shortcut_iterator.h"
+#include "suggest/core/dictionary/property/historical_info.h"
 #include "suggest/core/dictionary/property/word_property.h"
 #include "suggest/core/dictionary/word_attributes.h"
 #include "utils/int_array_view.h"
@@ -87,6 +88,11 @@
     virtual bool removeNgramEntry(const PrevWordsInfo *const prevWordsInfo,
             const CodePointArrayView wordCodePoints) = 0;
 
+    // Returns whether the update was success or not.
+    virtual bool updateCounter(const PrevWordsInfo *const prevWordsInfo,
+            const CodePointArrayView wordCodePoints, const bool isValidWord,
+            const HistoricalInfo historicalInfo) = 0;
+
     // Returns whether the flush was success or not.
     virtual bool flush(const char *const filePath) = 0;
 
diff --git a/native/jni/src/suggest/core/session/prev_words_info.h b/native/jni/src/suggest/core/session/prev_words_info.h
index 02e82a8..553d5ad 100644
--- a/native/jni/src/suggest/core/session/prev_words_info.h
+++ b/native/jni/src/suggest/core/session/prev_words_info.h
@@ -33,7 +33,7 @@
         clear();
     }
 
-    PrevWordsInfo(PrevWordsInfo &&prevWordsInfo)
+    PrevWordsInfo(const PrevWordsInfo &prevWordsInfo)
             : mPrevWordCount(prevWordsInfo.mPrevWordCount) {
         for (size_t i = 0; i < mPrevWordCount; ++i) {
             mPrevWordCodePointCount[i] = prevWordsInfo.mPrevWordCodePointCount[i];
@@ -73,6 +73,16 @@
         mIsBeginningOfSentence[0] = isBeginningOfSentence;
     }
 
+    size_t getPrevWordCount() const {
+        return mPrevWordCount;
+    }
+
+    // TODO: Remove.
+    const PrevWordsInfo getTrimmedPrevWordsInfo(const size_t maxPrevWordCount) const {
+        return PrevWordsInfo(mPrevWordCodePoints, mPrevWordCodePointCount, mIsBeginningOfSentence,
+                std::min(mPrevWordCount, maxPrevWordCount));
+    }
+
     bool isValid() const {
         if (mPrevWordCodePointCount[0] > 0) {
             return true;
@@ -112,7 +122,7 @@
     }
 
  private:
-    DISALLOW_COPY_AND_ASSIGN(PrevWordsInfo);
+    DISALLOW_ASSIGNMENT_OPERATOR(PrevWordsInfo);
 
     static int getWordId(const DictionaryStructureWithBufferPolicy *const dictStructurePolicy,
             const int *const wordCodePoints, const int wordCodePointCount,
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.cpp
index 40e393c..11f7b30 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.cpp
@@ -52,6 +52,7 @@
 const int Ver4PatriciaTriePolicy::MARGIN_TO_REFUSE_DYNAMIC_OPERATIONS = 1024;
 const int Ver4PatriciaTriePolicy::MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS =
         Ver4DictConstants::MAX_DICTIONARY_SIZE - MARGIN_TO_REFUSE_DYNAMIC_OPERATIONS;
+const int Ver4PatriciaTriePolicy::DUMMY_PROBABILITY_FOR_VALID_WORDS = 1;
 
 void Ver4PatriciaTriePolicy::createAndGetAllChildDicNodes(const DicNode *const dicNode,
         DicNodeVector *const childDicNodes) const {
@@ -339,11 +340,9 @@
     }
     if (prevWordIds[0] == NOT_A_WORD_ID) {
         if (prevWordsInfo->isNthPrevWordBeginningOfSentence(1 /* n */)) {
-            const std::vector<UnigramProperty::ShortcutProperty> shortcuts;
             const UnigramProperty beginningOfSentenceUnigramProperty(
                     true /* representsBeginningOfSentence */, true /* isNotAWord */,
-                    false /* isBlacklisted */, MAX_PROBABILITY /* probability */,
-                    HistoricalInfo(), &shortcuts);
+                    false /* isBlacklisted */, MAX_PROBABILITY /* probability */, HistoricalInfo());
             if (!addUnigramEntry(prevWordsInfo->getNthPrevWordCodePoints(1 /* n */),
                     &beginningOfSentenceUnigramProperty)) {
                 AKLOGE("Cannot add unigram entry for the beginning-of-sentence.");
@@ -414,6 +413,29 @@
     }
 }
 
+
+bool Ver4PatriciaTriePolicy::updateCounter(const PrevWordsInfo *const prevWordsInfo,
+        const CodePointArrayView wordCodePoints, const bool isValidWord,
+        const HistoricalInfo historicalInfo) {
+    if (!mBuffers->isUpdatable()) {
+        AKLOGI("Warning: updateCounter() is called for non-updatable dictionary.");
+        return false;
+    }
+    const int probability = isValidWord ? DUMMY_PROBABILITY_FOR_VALID_WORDS : NOT_A_PROBABILITY;
+    const UnigramProperty unigramProperty(false /* representsBeginningOfSentence */,
+            false /* isNotAWord */, false /*isBlacklisted*/, probability, historicalInfo);
+    if (!addUnigramEntry(wordCodePoints, &unigramProperty)) {
+        AKLOGE("Cannot update unigarm entry in updateCounter().");
+        return false;
+    }
+    const NgramProperty ngramProperty(wordCodePoints.toVector(), probability, historicalInfo);
+    if (!addNgramEntry(prevWordsInfo, &ngramProperty)) {
+        AKLOGE("Cannot update unigarm entry in updateCounter().");
+        return false;
+    }
+    return true;
+}
+
 bool Ver4PatriciaTriePolicy::flush(const char *const filePath) {
     if (!mBuffers->isUpdatable()) {
         AKLOGI("Warning: flush() is called for non-updatable dictionary. filePath: %s", filePath);
@@ -551,7 +573,7 @@
     }
     const UnigramProperty unigramProperty(ptNodeParams.representsBeginningOfSentence(),
             ptNodeParams.isNotAWord(), ptNodeParams.isBlacklisted(), ptNodeParams.getProbability(),
-            *historicalInfo, &shortcuts);
+            *historicalInfo, std::move(shortcuts));
     return WordProperty(wordCodePoints.toVector(), &unigramProperty, &ngrams);
 }
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.h
index 324a53e..995d776 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.h
@@ -118,6 +118,10 @@
     bool removeNgramEntry(const PrevWordsInfo *const prevWordsInfo,
             const CodePointArrayView wordCodePoints);
 
+    bool updateCounter(const PrevWordsInfo *const prevWordsInfo,
+            const CodePointArrayView wordCodePoints, const bool isValidWord,
+            const HistoricalInfo historicalInfo);
+
     bool flush(const char *const filePath);
 
     bool flushWithGC(const char *const filePath);
@@ -147,6 +151,7 @@
     // prevent the dictionary from overflowing.
     static const int MARGIN_TO_REFUSE_DYNAMIC_OPERATIONS;
     static const int MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS;
+    static const int DUMMY_PROBABILITY_FOR_VALID_WORDS;
 
     const Ver4DictBuffers::Ver4DictBuffersPtr mBuffers;
     const HeaderPolicy *const mHeaderPolicy;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.cpp
index 7800758..d3d684b 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.cpp
@@ -477,7 +477,7 @@
     }
     const UnigramProperty unigramProperty(ptNodeParams.representsBeginningOfSentence(),
             ptNodeParams.isNotAWord(), ptNodeParams.isBlacklisted(), ptNodeParams.getProbability(),
-            HistoricalInfo(), &shortcuts);
+            HistoricalInfo(), std::move(shortcuts));
     return WordProperty(wordCodePoints.toVector(), &unigramProperty, &ngrams);
 }
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.h
index a912d03..32a95bb 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.h
@@ -107,6 +107,14 @@
         return false;
     }
 
+    bool updateCounter(const PrevWordsInfo *const prevWordsInfo,
+            const CodePointArrayView wordCodePoints, const bool isValidWord,
+            const HistoricalInfo historicalInfo) {
+        // This method should not be called for non-updatable dictionary.
+        AKLOGI("Warning: updateCounter() is called for non-updatable dictionary.");
+        return false;
+    }
+
     bool flush(const char *const filePath) {
         // This method should not be called for non-updatable dictionary.
         AKLOGI("Warning: flush() is called for non-updatable dictionary.");
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
index 0badabf..41b109f 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
@@ -43,6 +43,7 @@
 const int Ver4PatriciaTriePolicy::MARGIN_TO_REFUSE_DYNAMIC_OPERATIONS = 1024;
 const int Ver4PatriciaTriePolicy::MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS =
         Ver4DictConstants::MAX_DICTIONARY_SIZE - MARGIN_TO_REFUSE_DYNAMIC_OPERATIONS;
+const int Ver4PatriciaTriePolicy::DUMMY_PROBABILITY_FOR_VALID_WORDS = 1;
 
 void Ver4PatriciaTriePolicy::createAndGetAllChildDicNodes(const DicNode *const dicNode,
         DicNodeVector *const childDicNodes) const {
@@ -298,11 +299,9 @@
         if (!prevWordsInfo->isNthPrevWordBeginningOfSentence(i + 1 /* n */)) {
             return false;
         }
-        const std::vector<UnigramProperty::ShortcutProperty> shortcuts;
         const UnigramProperty beginningOfSentenceUnigramProperty(
                 true /* representsBeginningOfSentence */, true /* isNotAWord */,
-                false /* isBlacklisted */, MAX_PROBABILITY /* probability */,
-                HistoricalInfo(), &shortcuts);
+                false /* isBlacklisted */, MAX_PROBABILITY /* probability */, HistoricalInfo());
         if (!addUnigramEntry(prevWordsInfo->getNthPrevWordCodePoints(1 /* n */),
                 &beginningOfSentenceUnigramProperty)) {
             AKLOGE("Cannot add unigram entry for the beginning-of-sentence.");
@@ -364,6 +363,32 @@
     }
 }
 
+bool Ver4PatriciaTriePolicy::updateCounter(const PrevWordsInfo *const prevWordsInfo,
+        const CodePointArrayView wordCodePoints, const bool isValidWord,
+        const HistoricalInfo historicalInfo) {
+    if (!mBuffers->isUpdatable()) {
+        AKLOGI("Warning: updateCounter() is called for non-updatable dictionary.");
+        return false;
+    }
+    // TODO: Have count up method in language model dict content.
+    const int probability = isValidWord ? DUMMY_PROBABILITY_FOR_VALID_WORDS : NOT_A_PROBABILITY;
+    const UnigramProperty unigramProperty(false /* representsBeginningOfSentence */,
+            false /* isNotAWord */, false /*isBlacklisted*/, probability, historicalInfo);
+    if (!addUnigramEntry(wordCodePoints, &unigramProperty)) {
+        AKLOGE("Cannot update unigarm entry in updateCounter().");
+        return false;
+    }
+    const NgramProperty ngramProperty(wordCodePoints.toVector(), probability, historicalInfo);
+    for (size_t i = 1; i <= prevWordsInfo->getPrevWordCount(); ++i) {
+        const PrevWordsInfo trimmedPrevWordsInfo(prevWordsInfo->getTrimmedPrevWordsInfo(i));
+        if (!addNgramEntry(&trimmedPrevWordsInfo, &ngramProperty)) {
+            AKLOGE("Cannot update ngram entry in updateCounter().");
+            return false;
+        }
+    }
+    return true;
+}
+
 bool Ver4PatriciaTriePolicy::flush(const char *const filePath) {
     if (!mBuffers->isUpdatable()) {
         AKLOGI("Warning: flush() is called for non-updatable dictionary. filePath: %s", filePath);
@@ -486,7 +511,7 @@
     }
     const UnigramProperty unigramProperty(probabilityEntry.representsBeginningOfSentence(),
             probabilityEntry.isNotAWord(), probabilityEntry.isBlacklisted(),
-            probabilityEntry.getProbability(), *historicalInfo, &shortcuts);
+            probabilityEntry.getProbability(), *historicalInfo, std::move(shortcuts));
     return WordProperty(wordCodePoints.toVector(), &unigramProperty, &ngrams);
 }
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h
index 598122b..662bb8d 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h
@@ -98,6 +98,10 @@
     bool removeNgramEntry(const PrevWordsInfo *const prevWordsInfo,
             const CodePointArrayView wordCodePoints);
 
+    bool updateCounter(const PrevWordsInfo *const prevWordsInfo,
+            const CodePointArrayView wordCodePoints, const bool isValidWord,
+            const HistoricalInfo historicalInfo);
+
     bool flush(const char *const filePath);
 
     bool flushWithGC(const char *const filePath);
@@ -127,6 +131,8 @@
     // prevent the dictionary from overflowing.
     static const int MARGIN_TO_REFUSE_DYNAMIC_OPERATIONS;
     static const int MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS;
+    // TODO: Remove
+    static const int DUMMY_PROBABILITY_FOR_VALID_WORDS;
 
     const Ver4DictBuffers::Ver4DictBuffersPtr mBuffers;
     const HeaderPolicy *const mHeaderPolicy;