diff --git a/packages/client/package.json b/packages/client/package.json
index bebad2bf9c..0af8ffac0b 100644
--- a/packages/client/package.json
+++ b/packages/client/package.json
@@ -22,6 +22,7 @@
 		"browser-image-resizer": "git+https://github.com/misskey-dev/browser-image-resizer#v2.2.1-misskey.3",
 		"chart.js": "4.1.1",
 		"chartjs-adapter-date-fns": "3.0.0",
+		"chartjs-chart-matrix": "^1.3.0",
 		"chartjs-plugin-gradient": "0.6.1",
 		"chartjs-plugin-zoom": "2.0.0",
 		"compare-versions": "5.0.1",
diff --git a/packages/client/src/pages/admin/overview.heatmap.vue b/packages/client/src/pages/admin/overview.heatmap.vue
new file mode 100644
index 0000000000..ce5b684ae8
--- /dev/null
+++ b/packages/client/src/pages/admin/overview.heatmap.vue
@@ -0,0 +1,233 @@
+<template>
+<div>
+	<MkLoading v-if="fetching"/>
+	<div v-show="!fetching" :class="$style.root" class="_panel">
+		<canvas ref="chartEl"></canvas>
+	</div>
+</div>
+</template>
+
+<script lang="ts" setup>
+import { markRaw, version as vueVersion, onMounted, onBeforeUnmount, nextTick } from 'vue';
+import {
+	Chart,
+	ArcElement,
+	LineElement,
+	BarElement,
+	PointElement,
+	BarController,
+	LineController,
+	CategoryScale,
+	LinearScale,
+	TimeScale,
+	Legend,
+	Title,
+	Tooltip,
+	SubTitle,
+	Filler,
+} from 'chart.js';
+import { enUS } from 'date-fns/locale';
+import tinycolor from 'tinycolor2';
+import * as os from '@/os';
+import 'chartjs-adapter-date-fns';
+import { defaultStore } from '@/store';
+import { useChartTooltip } from '@/scripts/use-chart-tooltip';
+import { MatrixController, MatrixElement } from 'chartjs-chart-matrix';
+import { chartVLine } from '@/scripts/chart-vline';
+
+Chart.register(
+	ArcElement,
+	LineElement,
+	BarElement,
+	PointElement,
+	BarController,
+	LineController,
+	CategoryScale,
+	LinearScale,
+	TimeScale,
+	Legend,
+	Title,
+	Tooltip,
+	SubTitle,
+	Filler,
+	MatrixController, MatrixElement,
+);
+
+const alpha = (hex, a) => {
+	const result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex)!;
+	const r = parseInt(result[1], 16);
+	const g = parseInt(result[2], 16);
+	const b = parseInt(result[3], 16);
+	return `rgba(${r}, ${g}, ${b}, ${a})`;
+};
+
+const chartEl = $ref<HTMLCanvasElement>(null);
+const now = new Date();
+let chartInstance: Chart = null;
+const chartLimit = 7 * 20;
+let fetching = $ref(true);
+
+const { handler: externalTooltipHandler } = useChartTooltip({
+	position: 'middle',
+});
+
+async function renderChart() {
+	if (chartInstance) {
+		chartInstance.destroy();
+	}
+
+	const getDate = (ago: number) => {
+		const y = now.getFullYear();
+		const m = now.getMonth();
+		const d = now.getDate();
+
+		return new Date(y, m, d - ago);
+	};
+
+	const format = (arr) => {
+		return arr.map((v, i) => {
+			const dt = getDate(i);
+			const iso = `${dt.getFullYear()}-${(dt.getMonth() + 1).toString().padStart(2, '0')}-${dt.getDate().toString().padStart(2, '0')}`;
+			return {
+				x: iso,
+				y: dt.getDay(),
+				d: iso,
+				v,
+			};
+		});
+	};
+
+	const raw = await os.api('charts/active-users', { limit: chartLimit, span: 'day' });
+
+	const gridColor = defaultStore.state.darkMode ? 'rgba(255, 255, 255, 0.1)' : 'rgba(0, 0, 0, 0.1)';
+
+	// フォントカラー
+	Chart.defaults.color = getComputedStyle(document.documentElement).getPropertyValue('--fg');
+
+	const color = '#3498db';
+
+	const max = Math.max(...raw.readWrite);
+
+	const marginEachCell = 4;
+
+	chartInstance = new Chart(chartEl, {
+		type: 'matrix',
+		data: {
+			datasets: [{
+				label: 'Read & Write',
+				data: format(raw.readWrite),
+				pointRadius: 0,
+				borderWidth: 0,
+				borderJoinStyle: 'round',
+				borderRadius: 4,
+				backgroundColor(c) {
+					const value = c.dataset.data[c.dataIndex].v;
+					const a = value / max;
+					return alpha(color, a);
+				},
+				fill: true,
+				width(c) {
+					const a = c.chart.chartArea ?? {};
+					// 20週間
+					return (a.right - a.left) / 20 - marginEachCell;
+				},
+				height(c) {
+					const a = c.chart.chartArea ?? {};
+					// 7日
+					return (a.bottom - a.top) / 7 - marginEachCell;
+				},
+			}],
+		},
+		options: {
+			aspectRatio: 2.8,
+			layout: {
+				padding: {
+					left: 8,
+					right: 0,
+					top: 0,
+					bottom: 0,
+				},
+			},
+			scales: {
+				x: {
+					type: 'time',
+					offset: true,
+					position: 'bottom',
+					time: {
+						unit: 'week',
+						round: 'week',
+						isoWeekday: 0,
+						displayFormats: {
+							week: 'MMM dd',
+						},
+					},
+					grid: {
+						display: false,
+						color: gridColor,
+						borderColor: 'rgb(0, 0, 0, 0)',
+					},
+					ticks: {
+						display: true,
+						maxRotation: 0,
+						autoSkipPadding: 8,
+					},
+				},
+				y: {
+					offset: true,
+					reverse: true,
+					position: 'right',
+					grid: {
+						display: false,
+						color: gridColor,
+						borderColor: 'rgb(0, 0, 0, 0)',
+					},
+					ticks: {
+						maxRotation: 0,
+						autoSkip: true,
+						padding: 1,
+						font: {
+							size: 9,
+						},
+						callback: (value, index, values) => ['', 'Mon', '', 'Wed', '', 'Fri', ''][value],
+					},
+				},
+			},
+			animation: false,
+			plugins: {
+				legend: {
+					display: false,
+				},
+				tooltip: {
+					enabled: false,
+					callbacks: {
+						title() {
+							return '';
+						},
+						label(context) {
+							const v = context.dataset.data[context.dataIndex];
+							return ['d: ' + v.d, 'v: ' + v.v.toFixed(2)];
+						},
+					},
+					//mode: 'index',
+					animation: {
+						duration: 0,
+					},
+					external: externalTooltipHandler,
+				},
+			},
+		},
+	});
+
+	fetching = false;
+}
+
+onMounted(async () => {
+	renderChart();
+});
+</script>
+
+<style lang="scss" module>
+.root {
+	padding: 20px;
+}
+</style>
diff --git a/packages/client/src/pages/admin/overview.vue b/packages/client/src/pages/admin/overview.vue
index 67f612e6b5..cc5b9b7b68 100644
--- a/packages/client/src/pages/admin/overview.vue
+++ b/packages/client/src/pages/admin/overview.vue
@@ -5,34 +5,47 @@
 			<template #header>Stats</template>
 			<XStats/>
 		</MkFolder>
+
 		<MkFolder class="item">
 			<template #header>Active users</template>
 			<XActiveUsers/>
 		</MkFolder>
+
+		<MkFolder class="item">
+			<template #header>Heatmap</template>
+			<XHeatmap/>
+		</MkFolder>
+
 		<MkFolder class="item">
 			<template #header>Moderators</template>
 			<XModerators/>
 		</MkFolder>
+
 		<MkFolder class="item">
 			<template #header>Federation</template>
 			<XFederation/>
 		</MkFolder>
+		
 		<MkFolder class="item">
 			<template #header>Instances</template>
 			<XInstances/>
 		</MkFolder>
+
 		<MkFolder class="item">
 			<template #header>Ap requests</template>
 			<XApRequests/>
 		</MkFolder>
+
 		<MkFolder class="item">
 			<template #header>New users</template>
 			<XUsers/>
 		</MkFolder>
+
 		<MkFolder class="item">
 			<template #header>Deliver queue</template>
 			<XQueue domain="deliver"/>
 		</MkFolder>
+
 		<MkFolder class="item">
 			<template #header>Inbox queue</template>
 			<XQueue domain="inbox"/>
@@ -51,6 +64,7 @@ import XUsers from './overview.users.vue';
 import XActiveUsers from './overview.active-users.vue';
 import XStats from './overview.stats.vue';
 import XModerators from './overview.moderators.vue';
+import XHeatmap from './overview.heatmap.vue';
 import MkTagCloud from '@/components/MkTagCloud.vue';
 import { version, url } from '@/config';
 import * as os from '@/os';
diff --git a/yarn.lock b/yarn.lock
index 25cd2980e7..3fdc9145fe 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -4956,6 +4956,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"chartjs-chart-matrix@npm:^1.3.0":
+  version: 1.3.0
+  resolution: "chartjs-chart-matrix@npm:1.3.0"
+  peerDependencies:
+    chart.js: ">=3.0.0"
+  checksum: d29a08f3ffd888a1b6c45be2cbeb8987c145a74b07a713c84001860669b200931517746c475537dd0893c57a739115fa96a68d3a113013aff28f3bee4494d5cc
+  languageName: node
+  linkType: hard
+
 "chartjs-plugin-gradient@npm:0.6.1":
   version: 0.6.1
   resolution: "chartjs-plugin-gradient@npm:0.6.1"
@@ -5165,6 +5174,7 @@ __metadata:
     browser-image-resizer: "git+https://github.com/misskey-dev/browser-image-resizer#v2.2.1-misskey.3"
     chart.js: 4.1.1
     chartjs-adapter-date-fns: 3.0.0
+    chartjs-chart-matrix: ^1.3.0
     chartjs-plugin-gradient: 0.6.1
     chartjs-plugin-zoom: 2.0.0
     compare-versions: 5.0.1