diff --git a/locales/ja-JP.yml b/locales/ja-JP.yml
index ebc41b0671..e5a37fdc20 100644
--- a/locales/ja-JP.yml
+++ b/locales/ja-JP.yml
@@ -413,6 +413,10 @@ common/views/pages/explore.vue:
   explore: "{host}を探索"
   users-info: "現在{users}ユーザーが登録されています"
 
+common/views/components/reactions-viewer.details.vue:
+  few-users: "{users}が{reaction}をリアクション"
+  many-users: "{users}と他{omitted}人が{reaction}をリアクション"
+
 common/views/components/url-preview.vue:
   enable-player: "プレイヤーを開く"
   disable-player: "プレイヤーを閉じる"
diff --git a/src/client/app/common/views/components/reactions-viewer.details.vue b/src/client/app/common/views/components/reactions-viewer.details.vue
new file mode 100644
index 0000000000..27eb860d5b
--- /dev/null
+++ b/src/client/app/common/views/components/reactions-viewer.details.vue
@@ -0,0 +1,103 @@
+<template>
+	<transition name="zoom-in-top">
+		<div class="buebdbiu" ref="popover" v-if="show">
+			<i18n path="few-users" v-if="users.length <= 10">
+				<span slot="users">{{ users.join(', ') }}</span>
+				<mk-reaction-icon slot="reaction" :reaction="reaction" ref="icon" />
+			</i18n>
+			<i18n path="many-users" v-if="10 < users.length">
+				<span slot="users">{{ users.slice(0, 10).join(', ') }}</span>
+				<span slot="ommited">{{ users.length - 10 }}</span>
+				<mk-reaction-icon slot="reaction" :reaction="reaction" ref="icon" />
+			</i18n>
+		</div>
+	</transition>
+</template>
+
+<script lang="ts">
+import Vue from 'vue';
+import i18n from '../../../i18n';
+
+export default Vue.extend({
+	i18n: i18n('common/views/components/reactions-viewer.details.vue'),
+	props: {
+		reaction: {
+			type: String,
+			required: true,
+		},
+		users: {
+			type: Array,
+			required: true,
+		},
+		source: {
+			required: true,
+		}
+	},
+	data() {
+		return {
+			show: false
+		};
+	},
+	mounted() {
+		this.show = true;
+
+		this.$nextTick(() => {
+			const popover = this.$refs.popover as any;
+
+			const rect = this.source.getBoundingClientRect();
+
+			const x = rect.left + window.pageXOffset + (this.source.offsetWidth / 2);
+			const y = rect.top + window.pageYOffset + this.source.offsetHeight;
+			popover.style.left = (x - 28) + 'px';
+			popover.style.top = (y + 16) + 'px';
+		});
+	}
+	methods: {
+		close() {
+			this.show = false;
+			setTimeout(this.destroyDom, 300);
+		}
+	}
+})
+</script>
+
+<style lang="stylus" scoped>
+.buebdbiu
+	$bgcolor = var(--popupBg)
+	z-index 10000
+	display block
+	position absolute
+	min-width max-content
+	max-width 240px
+	font-size 0.8em
+	padding 5px 8px
+	background $bgcolor
+	text-align center
+	color var(--text)
+	border-radius 4px
+	box-shadow 0 var(--lineWidth) 4px rgba(#000, 0.25)
+
+	&:before
+		content ""
+		pointer-events none
+		display block
+		position absolute
+		top -28px
+		left 12px
+		border-top solid 14px transparent
+		border-right solid 14px transparent
+		border-bottom solid 14px rgba(#000, 0.1)
+		border-left solid 14px transparent
+
+	&:after
+		content ""
+		pointer-events none
+		display block
+		position absolute
+		top -27px
+		left 12px
+		border-top solid 14px transparent
+		border-right solid 14px transparent
+		border-bottom solid 14px $bgcolor
+		border-left solid 14px transparent
+</style>
diff --git a/src/client/app/common/views/components/reactions-viewer.reaction.vue b/src/client/app/common/views/components/reactions-viewer.reaction.vue
index 02ee87b093..5bb9a9522e 100644
--- a/src/client/app/common/views/components/reactions-viewer.reaction.vue
+++ b/src/client/app/common/views/components/reactions-viewer.reaction.vue
@@ -5,6 +5,9 @@
 	@click="toggleReaction(reaction)"
 	v-if="count > 0"
 	v-particle="!isMe"
+	@mouseover="onMouseover"
+	@mouseleave="onMouseleave"
+	ref="reaction"
 >
 	<mk-reaction-icon :reaction="reaction" ref="icon"/>
 	<span>{{ count }}</span>
@@ -15,6 +18,7 @@
 import Vue from 'vue';
 import Icon from './reaction-icon.vue';
 import anime from 'animejs';
+import XDetails from './reactions-viewer.details.vue';
 
 export default Vue.extend({
 	props: {
@@ -40,6 +44,12 @@ export default Vue.extend({
 			default: true,
 		},
 	},
+	data() {
+		return {
+			details: null,
+			detailsTimeoutId: null
+		};
+	},
 	computed: {
 		isMe(): boolean {
 			return this.$store.getters.isSignedIn && this.$store.state.i.id === this.note.userId;
@@ -51,6 +61,7 @@ export default Vue.extend({
 	watch: {
 		count(newCount, oldCount) {
 			if (oldCount < newCount) this.anime();
+			if (this.details != null) this.openDetails();
 		},
 	},
 	methods: {
@@ -77,6 +88,35 @@ export default Vue.extend({
 				});
 			}
 		},
+		onMouseover() {
+			this.detailsTimeoutId = setTimeout(this.openDetails, 300);
+		},
+		onMouseleave() {
+			clearTimeout(this.detailsTimeoutId);
+			this.closeDetails();
+		},
+		openDetails() {
+			this.$root.api('notes/reactions', {
+				noteId: this.note.id
+			}).then((reactions: any[]) => {
+				const users = reactions.filter(x => x.type === this.reaction)
+					.sort((a, b) => new Date(a.createdAt).getTime() - new Date(b.createdAt).getTime())
+					.map(x => x.user.username);
+
+				this.closeDetails();
+				this.details = this.$root.new(XDetails, {
+					reaction: this.reaction,
+					users,
+					source: this.$refs.reaction
+				});
+			});
+		},
+		closeDetails() {
+			if (this.details != null) {
+				this.details.close();
+				this.details = null;
+			}
+		},
 		anime() {
 			if (this.$store.state.device.reduceMotion) return;
 			if (document.hidden) return;