diff --git a/native/jni/NativeFileList.mk b/native/jni/NativeFileList.mk
index 1e3775b..64704d9 100644
--- a/native/jni/NativeFileList.mk
+++ b/native/jni/NativeFileList.mk
@@ -126,6 +126,8 @@
     defines_test.cpp \
     suggest/core/layout/normal_distribution_2d_test.cpp \
     suggest/core/dictionary/bloom_filter_test.cpp \
+    suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content_test.cpp \
+    suggest/policyimpl/dictionary/structure/v4/content/probability_entry_test.cpp \
     suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer_test.cpp \
     suggest/policyimpl/dictionary/utils/trie_map_test.cpp \
     utils/autocorrection_threshold_utils_test.cpp \
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.cpp
index b165bf4..ae58475 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.cpp
@@ -22,4 +22,63 @@
     return mTrieMap.save(file);
 }
 
+bool LanguageModelDictContent::runGC(
+        const TerminalPositionLookupTable::TerminalIdMap *const terminalIdMap,
+        const LanguageModelDictContent *const originalContent,
+        int *const outNgramCount) {
+    return runGCInner(terminalIdMap, originalContent->mTrieMap.getEntriesInRootLevel(),
+            0 /* nextLevelBitmapEntryIndex */, outNgramCount);
+}
+
+ProbabilityEntry LanguageModelDictContent::getProbabilityEntry(
+        const WordIdArrayView prevWordIds, const int wordId) const {
+    if (!prevWordIds.empty()) {
+        // TODO: Read n-gram entry.
+        return ProbabilityEntry();
+    }
+    const TrieMap::Result result = mTrieMap.getRoot(wordId);
+    if (!result.mIsValid) {
+        // Not found.
+        return ProbabilityEntry();
+    }
+    return ProbabilityEntry::decode(result.mValue, mHasHistoricalInfo);
+}
+
+bool LanguageModelDictContent::setProbabilityEntry(const WordIdArrayView prevWordIds,
+        const int terminalId, const ProbabilityEntry *const probabilityEntry) {
+    if (!prevWordIds.empty()) {
+        // TODO: Add n-gram entry.
+        return false;
+    }
+    return mTrieMap.putRoot(terminalId, probabilityEntry->encode(mHasHistoricalInfo));
+}
+
+
+bool LanguageModelDictContent::runGCInner(
+        const TerminalPositionLookupTable::TerminalIdMap *const terminalIdMap,
+        const TrieMap::TrieMapRange trieMapRange,
+        const int nextLevelBitmapEntryIndex, int *const outNgramCount) {
+    for (auto &entry : trieMapRange) {
+        const auto it = terminalIdMap->find(entry.key());
+        if (it == terminalIdMap->end() || it->second == Ver4DictConstants::NOT_A_TERMINAL_ID) {
+            // The word has been removed.
+            continue;
+        }
+        if (!mTrieMap.put(it->second, entry.value(), nextLevelBitmapEntryIndex)) {
+            return false;
+        }
+        if (outNgramCount) {
+            *outNgramCount += 1;
+        }
+        if (entry.hasNextLevelMap()) {
+            if (!runGCInner(terminalIdMap, entry.getEntriesInNextLevel(),
+                    mTrieMap.getNextLevelBitmapEntryIndex(it->second, nextLevelBitmapEntryIndex),
+                    outNgramCount)) {
+                return false;
+            }
+        }
+    }
+    return true;
+}
+
 } // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.h
index 2639113..7f184f1 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.h
@@ -20,25 +20,53 @@
 #include <cstdio>
 
 #include "defines.h"
+#include "suggest/policyimpl/dictionary/structure/v4/content/probability_entry.h"
+#include "suggest/policyimpl/dictionary/structure/v4/content/terminal_position_lookup_table.h"
+#include "suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.h"
 #include "suggest/policyimpl/dictionary/utils/trie_map.h"
 #include "utils/byte_array_view.h"
+#include "utils/int_array_view.h"
 
 namespace latinime {
 
+/**
+ * Class representing language model.
+ *
+ * This class provides methods to get and store unigram/n-gram probability information and flags.
+ */
 class LanguageModelDictContent {
  public:
     LanguageModelDictContent(const ReadWriteByteArrayView trieMapBuffer,
             const bool hasHistoricalInfo)
-            : mTrieMap(trieMapBuffer) {}
+            : mTrieMap(trieMapBuffer), mHasHistoricalInfo(hasHistoricalInfo) {}
 
-    explicit LanguageModelDictContent(const bool hasHistoricalInfo) : mTrieMap() {}
+    explicit LanguageModelDictContent(const bool hasHistoricalInfo)
+            : mTrieMap(), mHasHistoricalInfo(hasHistoricalInfo) {}
+
+    bool isNearSizeLimit() const {
+        return mTrieMap.isNearSizeLimit();
+    }
 
     bool save(FILE *const file) const;
 
+    bool runGC(const TerminalPositionLookupTable::TerminalIdMap *const terminalIdMap,
+            const LanguageModelDictContent *const originalContent,
+            int *const outNgramCount);
+
+    ProbabilityEntry getProbabilityEntry(const WordIdArrayView prevWordIds, const int wordId) const;
+
+    bool setProbabilityEntry(const WordIdArrayView prevWordIds, const int wordId,
+            const ProbabilityEntry *const probabilityEntry);
+
  private:
     DISALLOW_COPY_AND_ASSIGN(LanguageModelDictContent);
 
     TrieMap mTrieMap;
+    const bool mHasHistoricalInfo;
+
+    bool runGCInner(const TerminalPositionLookupTable::TerminalIdMap *const terminalIdMap,
+            const TrieMap::TrieMapRange trieMapRange, const int nextLevelBitmapEntryIndex,
+            int *const outNgramCount);
 };
 } // namespace latinime
 #endif /* LATINIME_LANGUAGE_MODEL_DICT_CONTENT_H */
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_entry.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_entry.h
index 36ba82b..feff6b5 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_entry.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_entry.h
@@ -17,6 +17,9 @@
 #ifndef LATINIME_PROBABILITY_ENTRY_H
 #define LATINIME_PROBABILITY_ENTRY_H
 
+#include <climits>
+#include <cstdint>
+
 #include "defines.h"
 #include "suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.h"
 #include "suggest/policyimpl/dictionary/utils/historical_info.h"
@@ -67,6 +70,50 @@
         return &mHistoricalInfo;
     }
 
+    uint64_t encode(const bool hasHistoricalInfo) const {
+        uint64_t encodedEntry = static_cast<uint64_t>(mFlags);
+        if (hasHistoricalInfo) {
+            encodedEntry = (encodedEntry << (Ver4DictConstants::TIME_STAMP_FIELD_SIZE * CHAR_BIT))
+                    ^ static_cast<uint64_t>(mHistoricalInfo.getTimeStamp());
+            encodedEntry = (encodedEntry << (Ver4DictConstants::WORD_LEVEL_FIELD_SIZE * CHAR_BIT))
+                    ^ static_cast<uint64_t>(mHistoricalInfo.getLevel());
+            encodedEntry = (encodedEntry << (Ver4DictConstants::WORD_COUNT_FIELD_SIZE * CHAR_BIT))
+                    ^ static_cast<uint64_t>(mHistoricalInfo.getCount());
+        } else {
+            encodedEntry = (encodedEntry << (Ver4DictConstants::PROBABILITY_SIZE * CHAR_BIT))
+                    ^ static_cast<uint64_t>(mProbability);
+        }
+        return encodedEntry;
+    }
+
+    static ProbabilityEntry decode(const uint64_t encodedEntry, const bool hasHistoricalInfo) {
+        if (hasHistoricalInfo) {
+            const int flags = readFromEncodedEntry(encodedEntry,
+                    Ver4DictConstants::FLAGS_IN_PROBABILITY_FILE_SIZE,
+                    Ver4DictConstants::TIME_STAMP_FIELD_SIZE
+                            + Ver4DictConstants::WORD_LEVEL_FIELD_SIZE
+                            + Ver4DictConstants::WORD_COUNT_FIELD_SIZE);
+            const int timestamp = readFromEncodedEntry(encodedEntry,
+                    Ver4DictConstants::TIME_STAMP_FIELD_SIZE,
+                    Ver4DictConstants::WORD_LEVEL_FIELD_SIZE
+                            + Ver4DictConstants::WORD_COUNT_FIELD_SIZE);
+            const int level = readFromEncodedEntry(encodedEntry,
+                    Ver4DictConstants::WORD_LEVEL_FIELD_SIZE,
+                    Ver4DictConstants::WORD_COUNT_FIELD_SIZE);
+            const int count = readFromEncodedEntry(encodedEntry,
+                    Ver4DictConstants::WORD_COUNT_FIELD_SIZE, 0 /* pos */);
+            const HistoricalInfo historicalInfo(timestamp, level, count);
+            return ProbabilityEntry(flags, NOT_A_PROBABILITY, &historicalInfo);
+        } else {
+            const int flags = readFromEncodedEntry(encodedEntry,
+                    Ver4DictConstants::FLAGS_IN_PROBABILITY_FILE_SIZE,
+                    Ver4DictConstants::PROBABILITY_SIZE);
+            const int probability = readFromEncodedEntry(encodedEntry,
+                    Ver4DictConstants::PROBABILITY_SIZE, 0 /* pos */);
+            return ProbabilityEntry(flags, probability);
+        }
+    }
+
  private:
     // Copy constructor is public to use this class as a type of return value.
     DISALLOW_ASSIGNMENT_OPERATOR(ProbabilityEntry);
@@ -74,6 +121,11 @@
     const int mFlags;
     const int mProbability;
     const HistoricalInfo mHistoricalInfo;
+
+    static int readFromEncodedEntry(const uint64_t encodedEntry, const int size, const int pos) {
+        return static_cast<int>(
+                (encodedEntry >> (pos * CHAR_BIT)) & ((1ull << (size * CHAR_BIT)) - 1));
+    }
 };
 } // namespace latinime
 #endif /* LATINIME_PROBABILITY_ENTRY_H */
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_buffers.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_buffers.h
index 36671bc..d524dd6 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_buffers.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_buffers.h
@@ -90,6 +90,14 @@
         return &mProbabilityDictContent;
     }
 
+    AK_FORCE_INLINE LanguageModelDictContent *getMutableLanguageModelDictContent() {
+        return &mLanguageModelDictContent;
+    }
+
+    AK_FORCE_INLINE const LanguageModelDictContent *getLanguageModelDictContent() const {
+        return &mLanguageModelDictContent;
+    }
+
     AK_FORCE_INLINE BigramDictContent *getMutableBigramDictContent() {
         return &mBigramDictContent;
     }
diff --git a/native/jni/src/utils/int_array_view.h b/native/jni/src/utils/int_array_view.h
index 3ff01f5..4bc2487 100644
--- a/native/jni/src/utils/int_array_view.h
+++ b/native/jni/src/utils/int_array_view.h
@@ -61,6 +61,10 @@
         return mPtr[index];
     }
 
+    AK_FORCE_INLINE bool empty() const {
+        return size() == 0;
+    }
+
     AK_FORCE_INLINE size_t size() const {
         return mSize;
     }
@@ -76,5 +80,7 @@
     const size_t mSize;
 };
 
+using WordIdArrayView = IntArrayView;
+
 } // namespace latinime
 #endif // LATINIME_MEMORY_VIEW_H
diff --git a/native/jni/tests/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content_test.cpp b/native/jni/tests/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content_test.cpp
new file mode 100644
index 0000000..bf08344
--- /dev/null
+++ b/native/jni/tests/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content_test.cpp
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.h"
+
+#include <gtest/gtest.h>
+
+#include "utils/int_array_view.h"
+
+namespace latinime {
+namespace {
+
+TEST(LanguageModelDictContentTest, TestUnigramProbability) {
+    LanguageModelDictContent LanguageModelDictContent(false /* useHistoricalInfo */);
+
+    const int flag = 0xFF;
+    const int probability = 10;
+    const int wordId = 100;
+    const ProbabilityEntry probabilityEntry(flag, probability);
+    LanguageModelDictContent.setProbabilityEntry(WordIdArrayView(), wordId, &probabilityEntry);
+    const ProbabilityEntry entry =
+            LanguageModelDictContent.getProbabilityEntry(WordIdArrayView(), wordId);
+    EXPECT_EQ(flag, entry.getFlags());
+    EXPECT_EQ(probability, entry.getProbability());
+}
+
+TEST(LanguageModelDictContentTest, TestUnigramProbabilityWithHistoricalInfo) {
+    LanguageModelDictContent LanguageModelDictContent(true /* useHistoricalInfo */);
+
+    const int flag = 0xF0;
+    const int timestamp = 0x3FFFFFFF;
+    const int level = 3;
+    const int count = 10;
+    const int wordId = 100;
+    const HistoricalInfo historicalInfo(timestamp, level, count);
+    const ProbabilityEntry probabilityEntry(flag, NOT_A_PROBABILITY, &historicalInfo);
+    LanguageModelDictContent.setProbabilityEntry(WordIdArrayView(), wordId, &probabilityEntry);
+    const ProbabilityEntry entry =
+            LanguageModelDictContent.getProbabilityEntry(WordIdArrayView(), wordId);
+    EXPECT_EQ(flag, entry.getFlags());
+    EXPECT_EQ(timestamp, entry.getHistoricalInfo()->getTimeStamp());
+    EXPECT_EQ(level, entry.getHistoricalInfo()->getLevel());
+    EXPECT_EQ(count, entry.getHistoricalInfo()->getCount());
+}
+
+}  // namespace
+}  // namespace latinime
diff --git a/native/jni/tests/suggest/policyimpl/dictionary/structure/v4/content/probability_entry_test.cpp b/native/jni/tests/suggest/policyimpl/dictionary/structure/v4/content/probability_entry_test.cpp
new file mode 100644
index 0000000..db94550
--- /dev/null
+++ b/native/jni/tests/suggest/policyimpl/dictionary/structure/v4/content/probability_entry_test.cpp
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "suggest/policyimpl/dictionary/structure/v4/content/probability_entry.h"
+
+#include <gtest/gtest.h>
+
+#include "defines.h"
+
+namespace latinime {
+namespace {
+
+TEST(ProbabilityEntryTest, TestEncodeDecode) {
+    const int flag = 0xFF;
+    const int probability = 10;
+
+    const ProbabilityEntry entry(flag, probability);
+    const uint64_t encodedEntry = entry.encode(false /* hasHistoricalInfo */);
+    const ProbabilityEntry decodedEntry =
+            ProbabilityEntry::decode(encodedEntry, false /* hasHistoricalInfo */);
+    EXPECT_EQ(0xFF0Aull, encodedEntry);
+    EXPECT_EQ(flag, decodedEntry.getFlags());
+    EXPECT_EQ(probability, decodedEntry.getProbability());
+}
+
+TEST(ProbabilityEntryTest, TestEncodeDecodeWithHistoricalInfo) {
+    const int flag = 0xF0;
+    const int timestamp = 0x3FFFFFFF;
+    const int level = 3;
+    const int count = 10;
+
+    const HistoricalInfo historicalInfo(timestamp, level, count);
+    const ProbabilityEntry entry(flag, NOT_A_PROBABILITY, &historicalInfo);
+
+    const uint64_t encodedEntry = entry.encode(true /* hasHistoricalInfo */);
+    EXPECT_EQ(0xF03FFFFFFF030Aull, encodedEntry);
+    const ProbabilityEntry decodedEntry =
+            ProbabilityEntry::decode(encodedEntry, true /* hasHistoricalInfo */);
+
+    EXPECT_EQ(flag, decodedEntry.getFlags());
+    EXPECT_EQ(timestamp, decodedEntry.getHistoricalInfo()->getTimeStamp());
+    EXPECT_EQ(level, decodedEntry.getHistoricalInfo()->getLevel());
+    EXPECT_EQ(count, decodedEntry.getHistoricalInfo()->getCount());
+}
+
+}  // namespace
+}  // namespace latinime