diff --git a/README.md b/README.md
index 881f795..5e5f8b7 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,5 @@
 # VK Color Palette Manager
 
 ```
-composer require vektor-inc/vk-color-palette-manager
+composer require --no-dev vektor-inc/vk-color-palette-manager
 ```
\ No newline at end of file
diff --git a/src/VkColorPaletteManager.php b/src/VkColorPaletteManager.php
index 80432d0..cdcf1ac 100644
--- a/src/VkColorPaletteManager.php
+++ b/src/VkColorPaletteManager.php
@@ -5,7 +5,7 @@
  * @package vektor-inc/vk-color-palette-manager
  * @license GPL-2.0+
  *
- * @version 0.0.11
+ * @version 0.0.15
  */
 
 namespace VektorInc\VK_Color_Palette_Manager;
@@ -27,6 +27,7 @@ public function __construct() {
 		add_action( 'wp_enqueue_scripts', array( __CLASS__, 'add_color_palette_css' ), 11 );
 		// 11 指定が無いと先に読み込んでしまって効かない
 		add_action( 'enqueue_block_editor_assets', array( __CLASS__, 'add_color_palette_css_to_editor' ), 11 );
+		load_textdomain( 'vk-color-palette-manager', dirname( __FILE__ ) . '/languages/vk-color-palette-manager-' . get_locale() . '.mo' );
 	}
 
 	/**
@@ -51,8 +52,8 @@ public static function customize_register( $wp_customize ) {
 						'label'            => '',
 						'section'          => 'colors',
 						'type'             => 'text',
-						'custom_title_sub' => __( 'Color Palette Setting', 'vcpm_textdomain' ),
-						'custom_html'      => __( 'This color is reflected in the block editor\'s color palette.', 'vcpm_textdomain' ),
+						'custom_title_sub' => __( 'Color Palette Setting', 'vk-color-palette-manager' ),
+						'custom_html'      => __( 'This color is reflected in the block editor\'s color palette.', 'vk-color-palette-manager' ),
 						'priority'         => 1000,
 					)
 				)
@@ -69,7 +70,7 @@ public static function customize_register( $wp_customize ) {
 					'sanitize_callback' => 'sanitize_hex_color',
 				)
 			);
-			$label = __( 'Custom color', 'vcpm_textdomain' ) . ' ' . $i;
+			$label = __( 'Custom color', 'vk-color-palette-manager' ) . ' ' . $i;
 			$wp_customize->add_control(
 				new WP_Customize_Color_Control(
 					$wp_customize,
@@ -95,7 +96,7 @@ public static function add_color_array() {
 			for ( $i = 1; $i <= 5; $i++ ) {
 				if ( ! empty( $options_color[ 'color_custom_' . $i ] ) ) {
 					$vcm_add_color_array[] = array(
-						'name'  => __( 'Custom color', 'vcpm_textdomain' ) . ' ' . $i,
+						'name'  => __( 'Custom color', 'vk-color-palette-manager' ) . ' ' . $i,
 						'slug'  => 'vk-color-custom-' . $i,
 						'color' => $options_color[ 'color_custom_' . $i ],
 					);
@@ -114,14 +115,26 @@ public static function add_color_array() {
 	 */
 	public static function additional_color_palette( $editor_settings, $block_editor_context ) {
 		$add_color = self::add_color_array();
-		$editor_settings['__experimentalFeatures']['color']['palette']['core'] = array_merge(
-			$editor_settings['__experimentalFeatures']['color']['palette']['core'],
-			$add_color
-		);
-		$editor_settings['colors'] = array_merge(
-			$editor_settings['colors'],
-			$add_color
-		);
+		if ( ! empty( $add_color ) ) {
+			if ( ! empty( $editor_settings['__experimentalFeatures']['color']['palette']['default'] ) ) {
+				$editor_settings['__experimentalFeatures']['color']['palette']['default'] = array_merge(
+					$editor_settings['__experimentalFeatures']['color']['palette']['default'],
+					$add_color
+				);
+			} elseif ( ! empty( $editor_settings['__experimentalFeatures']['color']['palette']['core'] ) ) {
+				$editor_settings['__experimentalFeatures']['color']['palette']['core'] = array_merge(
+					$editor_settings['__experimentalFeatures']['color']['palette']['core'],
+					$add_color
+				);
+			} else {
+				$editor_settings['__experimentalFeatures']['color']['palette']['default'] = $add_color;
+				$editor_settings['__experimentalFeatures']['color']['palette']['core']    = $add_color;
+			}
+			$editor_settings['colors'] = array_merge(
+				$editor_settings['colors'],
+				$add_color
+			);
+		}
 		return $editor_settings;
 	}
 
diff --git a/src/languages/vk-color-palette-manager-ja.mo b/src/languages/vk-color-palette-manager-ja.mo
new file mode 100644
index 0000000..7132f02
Binary files /dev/null and b/src/languages/vk-color-palette-manager-ja.mo differ
diff --git a/src/languages/vk-color-palette-manager-ja.po b/src/languages/vk-color-palette-manager-ja.po
new file mode 100644
index 0000000..8834e39
--- /dev/null
+++ b/src/languages/vk-color-palette-manager-ja.po
@@ -0,0 +1,29 @@
+msgid ""
+msgstr ""
+"Project-Id-Version: Color Palette Manager\n"
+"POT-Creation-Date: 2021-11-18 15:43+0900\n"
+"PO-Revision-Date: 2021-11-18 17:04+0900\n"
+"Last-Translator: \n"
+"Language-Team: Vektor,Inc.\n"
+"Language: ja\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"X-Generator: Poedit 3.0\n"
+"X-Poedit-Basepath: ..\n"
+"Plural-Forms: nplurals=1; plural=0;\n"
+"X-Poedit-KeywordsList: __;_e\n"
+"X-Poedit-SourceCharset: UTF-8\n"
+"X-Poedit-SearchPath-0: VkColorPaletteManager.php\n"
+
+#: VkColorPaletteManager.php:55
+msgid "Color Palette Setting"
+msgstr "カラーパレット設定"
+
+#: VkColorPaletteManager.php:56
+msgid "This color is reflected in the block editor's color palette."
+msgstr "この色はエディターのカラーパレットに反映されます。"
+
+#: VkColorPaletteManager.php:73 VkColorPaletteManager.php:99
+msgid "Custom color"
+msgstr "カスタムカラー"