diff --git a/blue-monotone/code.ts b/blue-monotone/code.ts
new file mode 100644
index 0000000..8b8ef66
--- /dev/null
+++ b/blue-monotone/code.ts
@@ -0,0 +1,24 @@
+figma.showUI(__html__);
+
+figma.ui.onmessage = (msg) => {
+  if (msg.type === "convert-to-blue-monotone") {
+    const nodes = figma.currentPage.selection;
+
+    for (const node of nodes) {
+      if ("fills" in node) {
+        const fills = node.fills.map((fill) => {
+          if (fill.type === "SOLID") {
+            return {
+              ...fill,
+              color: { r: 0, g: 0, b: fill.color.b },
+            };
+          }
+          return fill;
+        });
+        node.fills = fills;
+      }
+    }
+  }
+
+  figma.closePlugin();
+};
diff --git a/blue-monotone/manifest.json b/blue-monotone/manifest.json
new file mode 100644
index 0000000..9e97545
--- /dev/null
+++ b/blue-monotone/manifest.json
@@ -0,0 +1,11 @@
+{
+  "id": "blue-monotone-plugin",
+  "name": "Blue Monotone Plugin",
+  "api": "1.0.0",
+  "main": "code.js",
+  "editorType": ["figma", "figjam"],
+  "networkAccess": {
+    "allowedDomains": ["none"]
+  },
+  "documentAccess": "dynamic-page"
+}
diff --git a/blue-monotone/tsconfig.json b/blue-monotone/tsconfig.json
new file mode 100644
index 0000000..3a7b407
--- /dev/null
+++ b/blue-monotone/tsconfig.json
@@ -0,0 +1,11 @@
+{
+  "compilerOptions": {
+    "target": "es6",
+    "lib": ["es6"],
+    "typeRoots": [
+      "../node_modules/@types",
+      "../node_modules/@figma"
+    ]
+  },
+  "include": ["**/*.ts"]
+}
diff --git a/blue-monotone/ui.html b/blue-monotone/ui.html
new file mode 100644
index 0000000..709b963
--- /dev/null
+++ b/blue-monotone/ui.html
@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <title>Blue Monotone Plugin</title>
+</head>
+<body>
+  <h1>Blue Monotone Plugin</h1>
+  <button id="convert-button">Convert to Blue Monotone</button>
+  <script>
+    document.getElementById('convert-button').onclick = () => {
+      parent.postMessage({ pluginMessage: { type: 'convert-to-blue-monotone' } }, '*');
+    };
+  </script>
+</body>
+</html>
