diff --git a/system/core/greeter.nix b/system/core/greeter.nix
index 588b4ca..8cba2ad 100644
--- a/system/core/greeter.nix
+++ b/system/core/greeter.nix
@@ -1,19 +1,16 @@
-{ config, pkgs, ... }:
+{ config, lib, pkgs, ... }:
 let
   rosePineHyprcursor = pkgs.callPackage ../../home-manager/hyprland/rose-pine-hyprcursor.nix { };
+  monitorConf = lib.concatMapStrings (m: "monitor = ${m}\n") config.cornflake.greeter.monitors;
   hyprGreetConf = pkgs.writeText "hyprland-greetd.conf" ''
-    monitor = DP-1, 5120x2880@60, 0x0, 2
-
-    monitor = DP-2, disable
-    monitor = DP-3, disable
-
+    ${monitorConf}
     env = HYPRCURSOR_THEME,rose-pine-hyprcursor
     env = HYPRCURSOR_SIZE,24
     env = XCURSOR_SIZE,24
 
     env = XDG_CURRENT_DESKTOP,Hyprland
     env = XDG_SESSION_TYPE,wayland
-    env = XDG_SESSION_DESKTOP,Hyprland"
+    env = XDG_SESSION_DESKTOP,Hyprland
 
     general {
       border_size = 0
@@ -33,39 +30,47 @@ let
   '';
 in
 {
-  services.greetd.enable = true;
-  services.greetd.settings.default_session = {
-    command = "${pkgs.hyprland}/bin/start-hyprland -- -c ${hyprGreetConf}";
-    user = "greeter";
+  options.cornflake.greeter.monitors = lib.mkOption {
+    type = lib.types.listOf lib.types.str;
+    default = [ ];
+    description = "greetd セッション用 Hyprland の monitor 設定";
   };
 
-  environment.systemPackages = [
-    rosePineHyprcursor
-  ];
+  config = {
+    services.greetd.enable = true;
+    services.greetd.settings.default_session = {
+      command = "${pkgs.hyprland}/bin/start-hyprland -- -c ${hyprGreetConf}";
+      user = "greeter";
+    };
 
-  programs.regreet = {
-    # greetd を Hyprland で動かす
-    enable = true;
-    theme.name = "Adwaita-dark";
-    iconTheme.name = "Papirus-Dark";
-    cursorTheme.name = "Bibata-Modern-Ice";
-    settings = {
-      appearance = {
-        greeting_msg = "Welcome back!";
-      };
-      widget = {
-        clock = {
-          format = "%H:%M";
-          resolution = "100ms";
-          timezone = "Asia/Tokyo";
-          label_width = 150;
+    environment.systemPackages = [
+      rosePineHyprcursor
+    ];
+
+    programs.regreet = {
+      # greetd を Hyprland で動かす
+      enable = true;
+      theme.name = "Adwaita-dark";
+      iconTheme.name = "Papirus-Dark";
+      cursorTheme.name = "Bibata-Modern-Ice";
+      settings = {
+        appearance = {
+          greeting_msg = "Welcome back!";
+        };
+        widget = {
+          clock = {
+            format = "%H:%M";
+            resolution = "100ms";
+            timezone = "Asia/Tokyo";
+            label_width = 150;
+          };
+        };
+        GTK = {
+          application_prefer_dark_theme = true;
+        };
+        background = {
+          path = "/usr/share/wallpaper/arknights-image-01.png";
         };
-      };
-      GTK = {
-        application_prefer_dark_theme = true;
-      };
-      background = {
-        path = "/usr/share/wallpaper/arknights-image-01.png";
       };
     };
   };