diff --git a/crates/voicevox_core_java_api/lib/src/main/java/jp/hiroshiba/voicevoxcore/Synthesizer.java b/crates/voicevox_core_java_api/lib/src/main/java/jp/hiroshiba/voicevoxcore/Synthesizer.java
index d6437a7d9..1a752236e 100644
--- a/crates/voicevox_core_java_api/lib/src/main/java/jp/hiroshiba/voicevoxcore/Synthesizer.java
+++ b/crates/voicevox_core_java_api/lib/src/main/java/jp/hiroshiba/voicevoxcore/Synthesizer.java
@@ -25,6 +25,31 @@ protected void finalize() throws Throwable {
     super.finalize();
   }
 
+  /**
+   * ハードウェアアクセラレーションがGPUモードかどうかを返す。
+   *
+   * @return ハードウェアアクセラレーションがGPUモードかどうか。
+   */
+  public boolean isGpuMode() {
+    return rsIsGpuMode();
+  }
+
+  /**
+   * メタ情報を取得する。
+   *
+   * @return メタ情報。
+   */
+  @Nonnull
+  public VoiceModel.SpeakerMeta[] getMetas() {
+    Gson gson = new Gson();
+    String metasJson = rsGetMetasJson();
+    VoiceModel.SpeakerMeta[] rawMetas = gson.fromJson(metasJson, VoiceModel.SpeakerMeta[].class);
+    if (rawMetas == null) {
+      throw new NullPointerException("metas");
+    }
+    return rawMetas;
+  }
+
   /**
    * モデルを読み込む。
    *
@@ -242,6 +267,11 @@ public TtsConfigurator tts(String text, int styleId) {
 
   private native void rsNew(OpenJtalk openJtalk, Builder builder);
 
+  private native boolean rsIsGpuMode();
+
+  @Nonnull
+  private native String rsGetMetasJson();
+
   private native void rsLoadVoiceModel(VoiceModel voiceModel) throws InvalidModelDataException;
 
   private native void rsUnloadVoiceModel(String voiceModelId);
diff --git a/crates/voicevox_core_java_api/lib/src/main/java/jp/hiroshiba/voicevoxcore/VoicevoxCoreInfo.java b/crates/voicevox_core_java_api/lib/src/main/java/jp/hiroshiba/voicevoxcore/VoicevoxCoreInfo.java
index e2ab2b93d..fbd0c3d42 100644
--- a/crates/voicevox_core_java_api/lib/src/main/java/jp/hiroshiba/voicevoxcore/VoicevoxCoreInfo.java
+++ b/crates/voicevox_core_java_api/lib/src/main/java/jp/hiroshiba/voicevoxcore/VoicevoxCoreInfo.java
@@ -16,7 +16,11 @@ public class VoicevoxCoreInfo extends Dll {
    */
   @Nonnull
   public static String getVersion() {
-    return rsGetVersion();
+    String version = rsGetVersion();
+    if (version == null) {
+      throw new NullPointerException("version");
+    }
+    return version;
   }
 
   /**
@@ -28,7 +32,11 @@ public static String getVersion() {
   public static SupportedDevices getSupportedDevices() {
     Gson gson = new Gson();
     String supportedDevicesJson = rsGetSupportedDevicesJson();
-    return gson.fromJson(supportedDevicesJson, SupportedDevices.class);
+    SupportedDevices supportedDevices = gson.fromJson(supportedDevicesJson, SupportedDevices.class);
+    if (supportedDevices == null) {
+      throw new NullPointerException("supported_devices");
+    }
+    return supportedDevices;
   }
 
   @Nonnull
diff --git a/crates/voicevox_core_java_api/lib/src/test/java/jp/hiroshiba/voicevoxcore/InfoTest.java b/crates/voicevox_core_java_api/lib/src/test/java/jp/hiroshiba/voicevoxcore/InfoTest.java
index 7fe03c468..8d8580e71 100644
--- a/crates/voicevox_core_java_api/lib/src/test/java/jp/hiroshiba/voicevoxcore/InfoTest.java
+++ b/crates/voicevox_core_java_api/lib/src/test/java/jp/hiroshiba/voicevoxcore/InfoTest.java
@@ -8,7 +8,7 @@
 
 import org.junit.jupiter.api.Test;
 
-class MetaTest {
+class InfoTest {
   @Test
   void checkVersion() {
     assertNotNull(VoicevoxCoreInfo.getVersion());
diff --git a/crates/voicevox_core_java_api/lib/src/test/java/jp/hiroshiba/voicevoxcore/SynthesizerTest.java b/crates/voicevox_core_java_api/lib/src/test/java/jp/hiroshiba/voicevoxcore/SynthesizerTest.java
index efa91eed8..514cf463f 100644
--- a/crates/voicevox_core_java_api/lib/src/test/java/jp/hiroshiba/voicevoxcore/SynthesizerTest.java
+++ b/crates/voicevox_core_java_api/lib/src/test/java/jp/hiroshiba/voicevoxcore/SynthesizerTest.java
@@ -8,6 +8,7 @@
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.List;
+
 import jp.hiroshiba.voicevoxcore.exceptions.InferenceFailedException;
 import jp.hiroshiba.voicevoxcore.exceptions.InvalidModelDataException;
 import org.junit.jupiter.api.Test;
@@ -18,6 +19,15 @@ interface MoraCheckCallback {
     boolean check(Mora mora, Mora otherMora);
   }
 
+  @Test
+  void checkIsGpuMode() {
+    OpenJtalk openJtalk = loadOpenJtalk();
+    Synthesizer synthesizer = Synthesizer.builder(openJtalk)
+        .accelerationMode(Synthesizer.AccelerationMode.CPU)
+        .build();
+    assertFalse(synthesizer.isGpuMode());
+  }
+
   boolean checkAllMoras(
       List<AccentPhrase> accentPhrases,
       List<AccentPhrase> otherAccentPhrases,
@@ -40,9 +50,17 @@ void checkModel() throws InvalidModelDataException {
     VoiceModel model = loadModel();
     OpenJtalk openJtalk = loadOpenJtalk();
     Synthesizer synthesizer = Synthesizer.builder(openJtalk).build();
+
+    assertTrue(synthesizer.getMetas().length == 0);
+
     synthesizer.loadVoiceModel(model);
+
+    assertTrue(synthesizer.getMetas().length >= 1);
     assertTrue(synthesizer.isLoadedVoiceModel(model.id));
+
     synthesizer.unloadVoiceModel(model.id);
+
+    assertTrue(synthesizer.getMetas().length == 0);
     assertFalse(synthesizer.isLoadedVoiceModel(model.id));
   }
 
@@ -63,28 +81,23 @@ void checkAccentPhrases() throws InferenceFailedException, InvalidModelDataExcep
     OpenJtalk openJtalk = loadOpenJtalk();
     Synthesizer synthesizer = Synthesizer.builder(openJtalk).build();
     synthesizer.loadVoiceModel(model);
-    List<AccentPhrase> accentPhrases =
-        synthesizer.createAccentPhrases("こんにちは", model.metas[0].styles[0].id);
-    List<AccentPhrase> accentPhrases2 =
-        synthesizer.replaceMoraPitch(accentPhrases, model.metas[1].styles[0].id);
+    List<AccentPhrase> accentPhrases = synthesizer.createAccentPhrases("こんにちは", model.metas[0].styles[0].id);
+    List<AccentPhrase> accentPhrases2 = synthesizer.replaceMoraPitch(accentPhrases, model.metas[1].styles[0].id);
     assertTrue(
         checkAllMoras(
             accentPhrases, accentPhrases2, (mora, otherMora) -> mora.pitch != otherMora.pitch));
-    List<AccentPhrase> accentPhrases3 =
-        synthesizer.replacePhonemeLength(accentPhrases, model.metas[1].styles[0].id);
+    List<AccentPhrase> accentPhrases3 = synthesizer.replacePhonemeLength(accentPhrases, model.metas[1].styles[0].id);
     assertTrue(
         checkAllMoras(
             accentPhrases,
             accentPhrases3,
             (mora, otherMora) -> mora.vowelLength != otherMora.vowelLength));
-    List<AccentPhrase> accentPhrases4 =
-        synthesizer.replaceMoraData(accentPhrases, model.metas[1].styles[0].id);
+    List<AccentPhrase> accentPhrases4 = synthesizer.replaceMoraData(accentPhrases, model.metas[1].styles[0].id);
     assertTrue(
         checkAllMoras(
             accentPhrases,
             accentPhrases4,
-            (mora, otherMora) ->
-                mora.pitch != otherMora.pitch && mora.vowelLength != otherMora.vowelLength));
+            (mora, otherMora) -> mora.pitch != otherMora.pitch && mora.vowelLength != otherMora.vowelLength));
   }
 
   @Test
diff --git a/crates/voicevox_core_java_api/src/synthesizer.rs b/crates/voicevox_core_java_api/src/synthesizer.rs
index 9307c11b7..35fb6b6d0 100644
--- a/crates/voicevox_core_java_api/src/synthesizer.rs
+++ b/crates/voicevox_core_java_api/src/synthesizer.rs
@@ -56,6 +56,37 @@ unsafe extern "system" fn Java_jp_hiroshiba_voicevoxcore_Synthesizer_rsNew<'loca
         Ok(())
     })
 }
+#[no_mangle]
+unsafe extern "system" fn Java_jp_hiroshiba_voicevoxcore_Synthesizer_rsIsGpuMode<'local>(
+    env: JNIEnv<'local>,
+    this: JObject<'local>,
+) -> jboolean {
+    throw_if_err(env, false, |env| {
+        let internal = env
+            .get_rust_field::<_, _, Arc<voicevox_core::Synthesizer>>(&this, "handle")?
+            .clone();
+
+        Ok(internal.is_gpu_mode())
+    })
+    .into()
+}
+#[no_mangle]
+unsafe extern "system" fn Java_jp_hiroshiba_voicevoxcore_Synthesizer_rsGetMetasJson<'local>(
+    env: JNIEnv<'local>,
+    this: JObject<'local>,
+) -> jobject {
+    throw_if_err(env, std::ptr::null_mut(), |env| {
+        let internal = env
+            .get_rust_field::<_, _, Arc<voicevox_core::Synthesizer>>(&this, "handle")?
+            .clone();
+
+        let metas_json = serde_json::to_string(&internal.metas()).expect("should not fail");
+
+        let j_metas_json = env.new_string(metas_json)?;
+
+        Ok(j_metas_json.into_raw())
+    })
+}
 
 #[no_mangle]
 unsafe extern "system" fn Java_jp_hiroshiba_voicevoxcore_Synthesizer_rsLoadVoiceModel<'local>(
diff --git a/crates/voicevox_core_python_api/python/voicevox_core/_rust.pyi b/crates/voicevox_core_python_api/python/voicevox_core/_rust.pyi
index 62de7b0e6..034e66908 100644
--- a/crates/voicevox_core_python_api/python/voicevox_core/_rust.pyi
+++ b/crates/voicevox_core_python_api/python/voicevox_core/_rust.pyi
@@ -107,7 +107,7 @@ class Synthesizer:
         """ハードウェアアクセラレーションがGPUモードかどうか。"""
         ...
     @property
-    def metas(self) -> SpeakerMeta:
+    def metas(self) -> List[SpeakerMeta]:
         """メタ情報。"""
         ...
     async def load_voice_model(self, model: VoiceModel) -> None: