diff --git a/packages/frontend/src/components/MkActiveUsersHeatmap.vue b/packages/frontend/src/components/MkActiveUsersHeatmap.vue
index 6b89a012f..744193dd5 100644
--- a/packages/frontend/src/components/MkActiveUsersHeatmap.vue
+++ b/packages/frontend/src/components/MkActiveUsersHeatmap.vue
@@ -132,12 +132,10 @@ async function renderChart() {
 				fill: true,
 				width(c) {
 					const a = c.chart.chartArea ?? {};
-					// 20週間
 					return (a.right - a.left) / weeks - marginEachCell;
 				},
 				height(c) {
 					const a = c.chart.chartArea ?? {};
-					// 7日
 					return (a.bottom - a.top) / 7 - marginEachCell;
 				},
 			}],
diff --git a/packages/frontend/src/components/MkChart.vue b/packages/frontend/src/components/MkChart.vue
index fbbc231b8..94cffa12c 100644
--- a/packages/frontend/src/components/MkChart.vue
+++ b/packages/frontend/src/components/MkChart.vue
@@ -39,6 +39,7 @@ import * as os from '@/os';
 import { defaultStore } from '@/store';
 import { useChartTooltip } from '@/scripts/use-chart-tooltip';
 import { chartVLine } from '@/scripts/chart-vline';
+import { alpha } from '@/scripts/color';
 
 const props = defineProps({
 	src: {
@@ -101,13 +102,6 @@ Chart.register(
 
 const sum = (...arr) => arr.reduce((r, a) => r.map((b, i) => a[i] + b));
 const negate = arr => arr.map(x => -x);
-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 colors = {
 	blue: '#008FFB',
diff --git a/packages/frontend/src/components/MkInstanceStats.vue b/packages/frontend/src/components/MkInstanceStats.vue
index 41f6f9ffd..f01bb7426 100644
--- a/packages/frontend/src/components/MkInstanceStats.vue
+++ b/packages/frontend/src/components/MkInstanceStats.vue
@@ -43,6 +43,13 @@
 		</div>
 	</MkFolder>
 
+	<MkFolder class="item">
+		<template #header>Retention rate</template>
+		<div class="_panel" :class="$style.retention">
+			<MkRetentionHeatmap/>
+		</div>
+	</MkFolder>
+
 	<MkFolder class="item">
 		<template #header>Federation</template>
 		<div :class="$style.federation">
@@ -88,6 +95,7 @@ import * as os from '@/os';
 import { i18n } from '@/i18n';
 import MkActiveUsersHeatmap from '@/components/MkActiveUsersHeatmap.vue';
 import MkFolder from '@/components/MkFolder.vue';
+import MkRetentionHeatmap from '@/components/MkRetentionHeatmap.vue';
 
 Chart.register(
 	ArcElement,
@@ -224,6 +232,11 @@ onMounted(() => {
 	margin-bottom: 16px;
 }
 
+.retention {
+	padding: 16px;
+	margin-bottom: 16px;
+}
+
 .federation {
 	&:global {
 		> .pies {
diff --git a/packages/frontend/src/components/MkRetentionHeatmap.vue b/packages/frontend/src/components/MkRetentionHeatmap.vue
new file mode 100644
index 000000000..cdfbd0d9a
--- /dev/null
+++ b/packages/frontend/src/components/MkRetentionHeatmap.vue
@@ -0,0 +1,218 @@
+<template>
+<div ref="rootEl">
+	<MkLoading v-if="fetching"/>
+	<div v-else>
+		<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';
+import { alpha } from '@/scripts/color';
+
+Chart.register(
+	ArcElement,
+	LineElement,
+	BarElement,
+	PointElement,
+	BarController,
+	LineController,
+	CategoryScale,
+	LinearScale,
+	TimeScale,
+	Legend,
+	Title,
+	Tooltip,
+	SubTitle,
+	Filler,
+	MatrixController, MatrixElement,
+);
+
+const rootEl = $ref<HTMLDivElement>(null);
+const chartEl = $ref<HTMLCanvasElement>(null);
+const now = new Date();
+let chartInstance: Chart = null;
+let fetching = $ref(true);
+
+const { handler: externalTooltipHandler } = useChartTooltip({
+	position: 'middle',
+});
+
+async function renderChart() {
+	if (chartInstance) {
+		chartInstance.destroy();
+	}
+
+	const wide = rootEl.offsetWidth > 600;
+	const narrow = rootEl.offsetWidth < 400;
+
+	const maxDays = wide ? 20 : narrow ? 10 : 15;
+
+	const raw = await os.api('retention', { });
+
+	const data = [];
+	for (const record of raw) {
+		let i = 0;
+		for (const date of Object.keys(record.data).sort((a, b) => new Date(a).getTime() - new Date(b).getTime())) {
+			data.push({
+				x: i,
+				y: record.createdAt,
+				v: record.data[date],
+			});
+			i++;
+		}
+	}
+
+	console.log(data);
+
+	fetching = false;
+
+	await nextTick();
+
+	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 = defaultStore.state.darkMode ? '#b4e900' : '#86b300';
+
+	// 視覚上の分かりやすさのため上から最も大きい3つの値の平均を最大値とする
+	//const max = raw.readWrite.slice().sort((a, b) => b - a).slice(0, 3).reduce((a, b) => a + b, 0) / 3;
+	const max = 4;
+
+	const marginEachCell = 6;
+
+	chartInstance = new Chart(chartEl, {
+		type: 'matrix',
+		data: {
+			datasets: [{
+				label: 'Active',
+				data: data,
+				pointRadius: 0,
+				borderWidth: 0,
+				borderJoinStyle: 'round',
+				borderRadius: 3,
+				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 ?? {};
+					return (a.right - a.left) / maxDays - marginEachCell;
+				},
+				height(c) {
+					const a = c.chart.chartArea ?? {};
+					return (a.bottom - a.top) / maxDays - (marginEachCell / 1.5);
+				},
+			}],
+		},
+		options: {
+			aspectRatio: wide ? 2 : narrow ? 2 : 2,
+			layout: {
+				padding: {
+					left: 8,
+					right: 0,
+					top: 0,
+					bottom: 0,
+				},
+			},
+			scales: {
+				x: {
+					position: 'top',
+					suggestedMax: maxDays,
+					grid: {
+						display: false,
+						color: gridColor,
+						borderColor: 'rgb(0, 0, 0, 0)',
+					},
+					ticks: {
+						display: true,
+						maxRotation: 0,
+						autoSkipPadding: 8,
+					},
+				},
+				y: {
+					type: 'time',
+					min: new Date(new Date().getFullYear(), new Date().getMonth(), new Date().getDate() - maxDays),
+					offset: true,
+					reverse: true,
+					position: 'left',
+					time: {
+						unit: 'day',
+						round: 'day',
+					},
+					grid: {
+						display: false,
+						color: gridColor,
+						borderColor: 'rgb(0, 0, 0, 0)',
+					},
+					ticks: {
+						maxRotation: 0,
+						autoSkip: true,
+						padding: 1,
+						font: {
+							size: 9,
+						},
+					},
+				},
+			},
+			animation: false,
+			plugins: {
+				legend: {
+					display: false,
+				},
+				tooltip: {
+					enabled: false,
+					callbacks: {
+						title(context) {
+							const v = context[0].dataset.data[context[0].dataIndex];
+							return v.d;
+						},
+						label(context) {
+							const v = context.dataset.data[context.dataIndex];
+							return ['Active: ' + v.v];
+						},
+					},
+					//mode: 'index',
+					animation: {
+						duration: 0,
+					},
+					external: externalTooltipHandler,
+				},
+			},
+		},
+	});
+}
+
+onMounted(async () => {
+	renderChart();
+});
+</script>
diff --git a/packages/frontend/src/pages/admin/overview.retention.vue b/packages/frontend/src/pages/admin/overview.retention.vue
index feac6f811..25de8a57c 100644
--- a/packages/frontend/src/pages/admin/overview.retention.vue
+++ b/packages/frontend/src/pages/admin/overview.retention.vue
@@ -1,49 +1,15 @@
 <template>
-<div>
-	<MkLoading v-if="fetching"/>
-	<div v-else :class="$style.root">
-		<div v-for="row in retention" class="row">
-			<div v-for="value in getValues(row)" v-tooltip="value.percentage" class="cell">
-			</div>
-		</div>
-	</div>
+<div class="_panel" :class="$style.root">
+	<MkRetentionHeatmap/>
 </div>
 </template>
 
 <script lang="ts" setup>
-import { onMounted, onUnmounted, ref } from 'vue';
-import * as os from '@/os';
-import number from '@/filters/number';
-import { i18n } from '@/i18n';
-
-let retention: any = $ref(null);
-let fetching = $ref(true);
-
-function getValues(row) {
-	const data = [];
-	for (const key in row.data) {
-		data.push({
-			date: new Date(key),
-			value: number(row.data[key]),
-			percentage: `${Math.ceil(row.data[key] / row.users) * 100}%`,
-		});
-	}
-	data.sort((a, b) => a.date > b.date);
-	return data;
-}
-
-onMounted(async () => {
-	retention = await os.apiGet('retention', {});
-
-	fetching = false;
-});
+import MkRetentionHeatmap from '@/components/MkRetentionHeatmap.vue';
 </script>
 
 <style lang="scss" module>
 .root {
-
-	&:global {
-
-	}
+	padding: 20px;
 }
 </style>