diff --git a/sjplayer/src/sjplayer/Context.d b/sjplayer/src/sjplayer/Context.d
index 3a39a92..1472ab0 100644
--- a/sjplayer/src/sjplayer/Context.d
+++ b/sjplayer/src/sjplayer/Context.d
@@ -21,6 +21,7 @@ import sjplayer.Actor,
        sjplayer.PostEffectControllerInterface,
        sjplayer.ProgramSet,
        sjplayer.ScheduledControllerInterface,
+       sjplayer.SquareElementScheduledController,
        sjplayer.VarStore,
        sjplayer.VarStoreScheduledController;
 
@@ -56,6 +57,10 @@ class Context {
           "circle",
           CircleElementScheduledControllerFactory(programs, varstore),
         ),
+        tuple(
+          "square",
+          SquareElementScheduledControllerFactory(programs, varstore),
+        ),
         tuple(
           "variable",
           VarStoreScheduledControllerFactory(varstore),
diff --git a/sjplayer/src/sjplayer/ProgramSet.d b/sjplayer/src/sjplayer/ProgramSet.d
index 0f7a92c..938c7b3 100644
--- a/sjplayer/src/sjplayer/ProgramSet.d
+++ b/sjplayer/src/sjplayer/ProgramSet.d
@@ -7,7 +7,8 @@ import std.meta,
 import sjplayer.Actor,
        sjplayer.Background,
        sjplayer.CircleElement,
-       sjplayer.PostEffect;
+       sjplayer.PostEffect,
+       sjplayer.SquareElement;
 
 ///
 class ProgramSet {
@@ -18,6 +19,7 @@ class ProgramSet {
       BackgroundProgram,
       CircleElementProgram,
       PostEffectProgram,
+      SquareElementProgram,
     );
 
   ///
diff --git a/sjplayer/src/sjplayer/SquareElement.d b/sjplayer/src/sjplayer/SquareElement.d
new file mode 100644
index 0000000..9b001f3
--- /dev/null
+++ b/sjplayer/src/sjplayer/SquareElement.d
@@ -0,0 +1,173 @@
+/// License: MIT
+module sjplayer.SquareElement;
+
+import gl4d;
+
+import sjplayer.ElementDrawer,
+       sjplayer.ElementInterface;
+
+///
+class SquareElement : ElementInterface {
+ public:
+  ///
+  static struct Instance {
+    ///
+    align(1) mat3 matrix = mat3.identity;
+    ///
+    align(1) float weight = 1;
+    ///
+    align(1) float smooth = 0.001;
+    ///
+    align(1) vec4 color = vec4(0, 0, 0, 0);
+  }
+
+  ///
+  void Initialize() {
+    alive        = false;
+    damage       = 0;
+    nearness_coe = 0;
+    instance     = instance.init;
+  }
+
+  override DamageCalculationResult CalculateDamage(vec2 p1, vec2 p2) const {
+    return DamageCalculationResult(0, 0);  // TODO:
+  }
+
+  ///
+  bool alive;
+  ///
+  float damage;
+  ///
+  float nearness_coe;
+  ///
+  Instance instance;
+  alias instance this;
+}
+
+///
+alias SquareElementDrawer = ElementDrawer!(
+    SquareElementProgram,
+    SquareElement,
+    [vec2(-1, 1), vec2(1, 1), vec2(1, -1), vec2(-1, -1)]);
+
+///
+class SquareElementProgram {
+ public:
+  ///
+  enum ShaderHeader = "#version 330 core
+#extension GL_ARB_explicit_uniform_location : enable";
+
+  ///
+  enum VertexShaderSrc = ShaderHeader ~ q{
+    layout(location = 0) in vec2 vert;
+
+    layout(location = 1) in vec3 m1;
+    layout(location = 2) in vec3 m2;
+    layout(location = 3) in vec3 m3;
+    layout(location = 4) in float weight;
+    layout(location = 5) in float smoooth;  // expected wrong spell
+    layout(location = 6) in vec4  color;
+
+    out vec2  uv_;
+    out float weight_;
+    out float smooth_;
+    out vec4  color_;
+
+    void main() {
+      mat3 m   = transpose(mat3(m1, m2, m3));
+      vec2 pos = (m * vec3(vert, 1)).xy;
+
+      uv_     = vert;
+      weight_ = weight;
+      smooth_ = smoooth;
+      color_  = color;
+      gl_Position = vec4(pos, 0, 1);
+    }
+  };
+  ///
+  enum FragmentShaderSrc = ShaderHeader ~ q{
+    in vec2  uv_;
+    in float weight_;
+    in float smooth_;
+    in vec4  color_;
+
+    out vec4 pixel_;
+
+    float square() {
+      float w = 1-weight_;
+      float s = smooth_;
+      return clamp(
+          smoothstep(w-s, w, abs(uv_.x)) +
+          smoothstep(w-s, w, abs(uv_.y)), 0, 1);
+    }
+
+    void main() {
+      pixel_    = color_;
+      pixel_.a *= square();
+    }
+  };
+
+  ///
+  this() {
+    ProgramLinker linker;
+    linker.vertex   = VertexShader.Compile(VertexShaderSrc);
+    linker.fragment = FragmentShader.Compile(FragmentShaderSrc);
+    program_ = linker.Link();
+    program_.Validate();
+  }
+
+  ///
+  void SetupVertexArray(ref VertexArrayRef vao,
+      ref ArrayBufferRef verts, ref ArrayBufferRef instances) {
+    with (VertexArrayAttacher()) {
+      // verts
+      type      = GL_FLOAT;
+      dimension = 2;
+      Attach(vao, verts);
+      ++index;
+
+      type    = GL_FLOAT;
+      divisor = 1;
+      stride  = SquareElement.Instance.sizeof;
+      offset  = 0;
+
+      // matrix
+      dimension = 3;
+      Attach(vao, instances);
+      offset += float.sizeof*3;
+      ++index;
+      Attach(vao, instances);
+      offset += float.sizeof*3;
+      ++index;
+      Attach(vao, instances);
+      offset += float.sizeof*3;
+      ++index;
+
+      // weight
+      dimension = 1;
+      Attach(vao, instances);
+      offset += float.sizeof*1;
+      ++index;
+
+      // smooth
+      dimension = 1;
+      Attach(vao, instances);
+      offset += float.sizeof*1;
+      ++index;
+
+      // color
+      dimension = 4;
+      Attach(vao, instances);
+      offset += float.sizeof*4;
+      ++index;
+    }
+  }
+
+  ///
+  void Use() {
+    program_.Use();
+  }
+
+ private:
+  ProgramRef program_;
+}
diff --git a/sjplayer/src/sjplayer/SquareElementScheduledController.d b/sjplayer/src/sjplayer/SquareElementScheduledController.d
new file mode 100644
index 0000000..419caf3
--- /dev/null
+++ b/sjplayer/src/sjplayer/SquareElementScheduledController.d
@@ -0,0 +1,32 @@
+/// License: MIT
+module sjplayer.SquareElementScheduledController;
+
+import std.typecons;
+
+import sjplayer.ElementScheduledControllerFactory,
+       sjplayer.ScheduledController,
+       sjplayer.SquareElement;
+
+///
+alias SquareElementScheduledController = ScheduledController!(
+    SquareElement,
+    [
+      "damage":       "damage",
+      "nearness_coe": "nearness_coe",
+      "weight":       "weight",
+      "smooth":       "smooth",
+      "color_r":      "color.r",
+      "color_g":      "color.g",
+      "color_b":      "color.b",
+      "color_a":      "color.a",
+    ]
+  );
+static assert(SquareElementScheduledController.AliveManagementAvailable);
+static assert(SquareElementScheduledController.MatrixModificationAvailable);
+static assert(SquareElementScheduledController.AutoInitializationAvailable);
+
+///
+alias SquareElementScheduledControllerFactory =
+  ElementScheduledControllerFactory!(
+      SquareElementScheduledController,
+      SquareElementDrawer);