diff --git a/src/converter/converter.cc b/src/converter/converter.cc
index 9ff075739..8e03cd872 100644
--- a/src/converter/converter.cc
+++ b/src/converter/converter.cc
@@ -455,37 +455,6 @@ bool Converter::StartPrediction(const ConversionRequest &request,
   return Predict(request, segments);
 }
 
-bool Converter::StartSuggestion(const ConversionRequest &original_request,
-                                Segments *segments) const {
-  const ConversionRequest request = CreateConversionRequestWithType(
-      original_request, ConversionRequest::SUGGESTION);
-  return Predict(request, segments);
-}
-
-bool Converter::StartPartialSuggestion(
-    const ConversionRequest &original_request, Segments *segments) const {
-  const size_t cursor = original_request.composer().GetCursor();
-  if (cursor == 0 || cursor == original_request.composer().GetLength()) {
-    return StartSuggestion(original_request, segments);
-  }
-
-  const ConversionRequest request = CreateConversionRequestWithType(
-      original_request, ConversionRequest::PARTIAL_SUGGESTION);
-  return Predict(request, segments);
-}
-
-bool Converter::StartPartialPrediction(
-    const ConversionRequest &original_request, Segments *segments) const {
-  const size_t cursor = original_request.composer().GetCursor();
-  if (cursor == 0 || cursor == original_request.composer().GetLength()) {
-    return StartPrediction(original_request, segments);
-  }
-
-  const ConversionRequest request = CreateConversionRequestWithType(
-      original_request, ConversionRequest::PARTIAL_PREDICTION);
-  return Predict(request, segments);
-}
-
 void Converter::FinishConversion(const ConversionRequest &request,
                                  Segments *segments) const {
   CommitUsageStats(segments, segments->history_segments_size(),
diff --git a/src/converter/converter.h b/src/converter/converter.h
index e7233117d..e83fe4580 100644
--- a/src/converter/converter.h
+++ b/src/converter/converter.h
@@ -71,15 +71,6 @@ class Converter final : public ConverterInterface {
   ABSL_MUST_USE_RESULT
   bool StartPrediction(const ConversionRequest &request,
                        Segments *segments) const override;
-  ABSL_MUST_USE_RESULT
-  bool StartSuggestion(const ConversionRequest &request,
-                       Segments *segments) const override;
-  ABSL_MUST_USE_RESULT
-  bool StartPartialPrediction(const ConversionRequest &request,
-                              Segments *segments) const override;
-  ABSL_MUST_USE_RESULT
-  bool StartPartialSuggestion(const ConversionRequest &request,
-                              Segments *segments) const override;
 
   void FinishConversion(const ConversionRequest &request,
                         Segments *segments) const override;
diff --git a/src/converter/converter_interface.h b/src/converter/converter_interface.h
index 919b3c097..703a35d20 100644
--- a/src/converter/converter_interface.h
+++ b/src/converter/converter_interface.h
@@ -68,21 +68,6 @@ class ConverterInterface {
   virtual bool StartPrediction(const ConversionRequest &request,
                                Segments *segments) const = 0;
 
-  // Starts suggestion for given request.
-  ABSL_MUST_USE_RESULT
-  virtual bool StartSuggestion(const ConversionRequest &request,
-                               Segments *segments) const = 0;
-
-  // Starts partial prediction for given request.
-  ABSL_MUST_USE_RESULT
-  virtual bool StartPartialPrediction(const ConversionRequest &request,
-                                      Segments *segments) const = 0;
-
-  // Starts partial suggestion for given request.
-  ABSL_MUST_USE_RESULT
-  virtual bool StartPartialSuggestion(const ConversionRequest &request,
-                                      Segments *segments) const = 0;
-
   // Finish conversion.
   // Segments are cleared. Context is not cleared
   virtual void FinishConversion(const ConversionRequest &request,
diff --git a/src/converter/converter_main.cc b/src/converter/converter_main.cc
index 65ecb343d..bfec77486 100644
--- a/src/converter/converter_main.cc
+++ b/src/converter/converter_main.cc
@@ -300,11 +300,12 @@ bool ExecCommand(const ConverterInterface &converter, const std::string &line,
           absl::GetFlag(FLAGS_max_conversion_candidates_size),
       .create_partial_candidates = request.auto_partial_suggestion(),
   };
-  const ConversionRequest conversion_request = ConversionRequest(
-      composer, request, context, *config, std::move(options));
 
   const std::string &func = fields[0];
   if (func == "startconversion" || func == "start" || func == "s") {
+    options.request_type = ConversionRequest::CONVERSION;
+    const ConversionRequest conversion_request = ConversionRequest(
+        composer, request, context, *config, std::move(options));
     CHECK_FIELDS_LENGTH(2);
     composer.SetPreeditTextForTestOnly(fields[1]);
     return converter.StartConversion(conversion_request, segments);
@@ -325,6 +326,9 @@ bool ExecCommand(const ConverterInterface &converter, const std::string &line,
     CHECK_FIELDS_LENGTH(2);
     return converter.StartReverseConversion(segments, fields[1]);
   } else if (func == "startprediction" || func == "predict" || func == "p") {
+    options.request_type = ConversionRequest::PREDICTION;
+    const ConversionRequest conversion_request = ConversionRequest(
+        composer, request, context, *config, std::move(options));
     if (fields.size() >= 2) {
       composer.SetPreeditTextForTestOnly(fields[1]);
       return converter.StartPrediction(conversion_request, segments);
@@ -332,13 +336,19 @@ bool ExecCommand(const ConverterInterface &converter, const std::string &line,
       return converter.StartPrediction(conversion_request, segments);
     }
   } else if (func == "startsuggestion" || func == "suggest") {
+    options.request_type = ConversionRequest::SUGGESTION;
+    const ConversionRequest conversion_request = ConversionRequest(
+        composer, request, context, *config, std::move(options));
     if (fields.size() >= 2) {
       composer.SetPreeditTextForTestOnly(fields[1]);
-      return converter.StartSuggestion(conversion_request, segments);
+      return converter.StartPrediction(conversion_request, segments);
     } else {
-      return converter.StartSuggestion(conversion_request, segments);
+      return converter.StartPrediction(conversion_request, segments);
     }
   } else if (func == "finishconversion" || func == "finish") {
+    options.request_type = ConversionRequest::CONVERSION;
+    const ConversionRequest conversion_request = ConversionRequest(
+        composer, request, context, *config, std::move(options));
     converter.FinishConversion(conversion_request, segments);
     return true;
   } else if (func == "resetconversion" || func == "reset") {
@@ -359,6 +369,9 @@ bool ExecCommand(const ConverterInterface &converter, const std::string &line,
         if (!(converter.CommitSegmentValue(segments, i, 0))) return false;
       }
     }
+    options.request_type = ConversionRequest::CONVERSION;
+    const ConversionRequest conversion_request = ConversionRequest(
+        composer, request, context, *config, std::move(options));
     converter.FinishConversion(conversion_request, segments);
     return true;
   } else if (func == "focussegmentvalue" || func == "focus") {
@@ -372,6 +385,9 @@ bool ExecCommand(const ConverterInterface &converter, const std::string &line,
     singleton_vector.push_back(NumberUtil::SimpleAtoi(fields[1]));
     return converter.CommitSegments(segments, singleton_vector);
   } else if (func == "resizesegment" || func == "resize") {
+    options.request_type = ConversionRequest::CONVERSION;
+    const ConversionRequest conversion_request = ConversionRequest(
+        composer, request, context, *config, std::move(options));
     if (fields.size() == 3) {
       return converter.ResizeSegment(segments, conversion_request,
                                      NumberUtil::SimpleAtoi(fields[1]),
diff --git a/src/converter/converter_mock.h b/src/converter/converter_mock.h
index 9512571f8..cfd6cee57 100644
--- a/src/converter/converter_mock.h
+++ b/src/converter/converter_mock.h
@@ -55,15 +55,6 @@ class StrictMockConverter : public ConverterInterface {
   MOCK_METHOD(bool, StartPrediction,
               (const ConversionRequest &request, Segments *segments),
               (const, override));
-  MOCK_METHOD(bool, StartSuggestion,
-              (const ConversionRequest &request, Segments *segments),
-              (const, override));
-  MOCK_METHOD(bool, StartPartialPrediction,
-              (const ConversionRequest &request, Segments *segments),
-              (const, override));
-  MOCK_METHOD(bool, StartPartialSuggestion,
-              (const ConversionRequest &request, Segments *segments),
-              (const, override));
   MOCK_METHOD(void, FinishConversion,
               (const ConversionRequest &request, Segments *segments),
               (const, override));
diff --git a/src/converter/converter_test.cc b/src/converter/converter_test.cc
index 490334653..728af7098 100644
--- a/src/converter/converter_test.cc
+++ b/src/converter/converter_test.cc
@@ -1022,7 +1022,7 @@ TEST_F(ConverterTest, StartSuggestion) {
                                     std::move(options));
 
     Segments segments;
-    EXPECT_TRUE(converter->StartSuggestion(request, &segments));
+    EXPECT_TRUE(converter->StartPrediction(request, &segments));
     EXPECT_EQ(segments.segments_size(), 1);
     ASSERT_TRUE(segments.segment(0).meta_candidates_size() >=
                 transliteration::HALF_ASCII);
@@ -1043,7 +1043,7 @@ TEST_F(ConverterTest, StartSuggestion) {
                                     std::move(options));
 
     Segments segments;
-    EXPECT_TRUE(converter->StartSuggestion(request, &segments));
+    EXPECT_TRUE(converter->StartPrediction(request, &segments));
     EXPECT_EQ(segments.segments_size(), 1);
     ASSERT_TRUE(segments.segment(0).meta_candidates_size() >=
                 transliteration::HALF_ASCII);
@@ -1059,7 +1059,7 @@ TEST_F(ConverterTest, StartPartialPrediction) {
   ConverterInterface *converter = engine->GetConverter();
   CHECK(converter);
   Segments segments;
-  EXPECT_TRUE(converter->StartPartialPrediction(
+  EXPECT_TRUE(converter->StartPrediction(
       ConvReq("わたしは", ConversionRequest::PARTIAL_PREDICTION), &segments));
   EXPECT_EQ(segments.segments_size(), 1);
   EXPECT_EQ(segments.segment(0).candidate(0).key, "わたしは");
@@ -1072,7 +1072,7 @@ TEST_F(ConverterTest, StartPartialSuggestion) {
   ConverterInterface *converter = engine->GetConverter();
   CHECK(converter);
   Segments segments;
-  EXPECT_TRUE(converter->StartPartialSuggestion(
+  EXPECT_TRUE(converter->StartPrediction(
       ConvReq("わたしは", ConversionRequest::PARTIAL_SUGGESTION), &segments));
   EXPECT_EQ(segments.segments_size(), 1);
   EXPECT_EQ(segments.segment(0).candidate(0).key, "わたしは");
@@ -1084,7 +1084,7 @@ TEST_F(ConverterTest, StartPartialPredictionMobile) {
   ConverterInterface *converter = engine->GetConverter();
   CHECK(converter);
   Segments segments;
-  EXPECT_TRUE(converter->StartPartialPrediction(
+  EXPECT_TRUE(converter->StartPrediction(
       ConvReq("わたしは", ConversionRequest::PARTIAL_PREDICTION), &segments));
   EXPECT_EQ(segments.segments_size(), 1);
   EXPECT_EQ(segments.segment(0).candidate(0).key, "わたしは");
@@ -1096,7 +1096,7 @@ TEST_F(ConverterTest, StartPartialSuggestionMobile) {
   ConverterInterface *converter = engine->GetConverter();
   CHECK(converter);
   Segments segments;
-  EXPECT_TRUE(converter->StartPartialSuggestion(
+  EXPECT_TRUE(converter->StartPrediction(
       ConvReq("わたしは", ConversionRequest::PARTIAL_SUGGESTION), &segments));
   EXPECT_EQ(segments.segments_size(), 1);
   EXPECT_EQ(segments.segment(0).candidate(0).key, "わたしは");
@@ -1245,7 +1245,7 @@ TEST_F(ConverterTest, VariantExpansionForSuggestion) {
   Segments segments;
   {
     // Dictionary suggestion
-    EXPECT_TRUE(converter.StartSuggestion(
+    EXPECT_TRUE(converter.StartPrediction(
         ConvReq("てすと", ConversionRequest::SUGGESTION), &segments));
     EXPECT_EQ(segments.conversion_segments_size(), 1);
     EXPECT_LE(1, segments.conversion_segment(0).candidates_size());
@@ -1256,7 +1256,7 @@ TEST_F(ConverterTest, VariantExpansionForSuggestion) {
   {
     // Realtime conversion
     segments.Clear();
-    EXPECT_TRUE(converter.StartSuggestion(
+    EXPECT_TRUE(converter.StartPrediction(
         ConvReq("てすとの", ConversionRequest::SUGGESTION), &segments));
     EXPECT_EQ(segments.conversion_segments_size(), 1);
     EXPECT_LE(1, segments.conversion_segment(0).candidates_size());
diff --git a/src/converter/quality_regression_util.cc b/src/converter/quality_regression_util.cc
index e8dc63b79..a930f6231 100644
--- a/src/converter/quality_regression_util.cc
+++ b/src/converter/quality_regression_util.cc
@@ -283,9 +283,9 @@ absl::StatusOr<bool> QualityRegressionUtil::ConvertAndTest(
     const ConversionRequest conv_req(
         composer, request_, context, config_,
         {.request_type = ConversionRequest::SUGGESTION});
-    if (!converter_->StartSuggestion(conv_req, &segments_)) {
-      return absl::UnknownError(
-          absl::StrCat("StartSuggestion failed: ", item.OutputAsTSV()));
+    if (!converter_->StartPrediction(conv_req, &segments_)) {
+      return absl::UnknownError(absl::StrCat(
+          "StartPrediction for suggestion failed: ", item.OutputAsTSV()));
     }
   } else if (command == kZeroQueryExpect || command == kZeroQueryNotExpect) {
     commands::Request request = request_;
@@ -298,9 +298,9 @@ absl::StatusOr<bool> QualityRegressionUtil::ConvertAndTest(
           composer, request, context, config_,
           {.request_type = ConversionRequest::SUGGESTION,
            .max_conversion_candidates_size = 10});
-      if (!converter_->StartSuggestion(conv_req, &segments_)) {
-        return absl::UnknownError(
-            absl::StrCat("StartSuggestion failed: ", item.OutputAsTSV()));
+      if (!converter_->StartPrediction(conv_req, &segments_)) {
+        return absl::UnknownError(absl::StrCat(
+            "StartSuggestion for suggestion failed: ", item.OutputAsTSV()));
       }
       if (!converter_->CommitSegmentValue(&segments_, 0, 0)) {
         return absl::UnknownError(
diff --git a/src/engine/minimal_engine.cc b/src/engine/minimal_engine.cc
index bed3aaa3f..b5c9bdce5 100644
--- a/src/engine/minimal_engine.cc
+++ b/src/engine/minimal_engine.cc
@@ -116,21 +116,6 @@ class MinimalConverter : public ConverterInterface {
     return AddAsIsCandidate(request, segments);
   }
 
-  bool StartSuggestion(const ConversionRequest &request,
-                       Segments *segments) const override {
-    return AddAsIsCandidate(request, segments);
-  }
-
-  bool StartPartialPrediction(const ConversionRequest &request,
-                              Segments *segments) const override {
-    return false;
-  }
-
-  bool StartPartialSuggestion(const ConversionRequest &request,
-                              Segments *segments) const override {
-    return false;
-  }
-
   void FinishConversion(const ConversionRequest &request,
                         Segments *segments) const override {}