diff --git a/packages/client/src/components/global/MkMisskeyFlavoredMarkdown.vue b/packages/client/src/components/global/MkMisskeyFlavoredMarkdown.vue
index c235b48354..896891d5e5 100644
--- a/packages/client/src/components/global/MkMisskeyFlavoredMarkdown.vue
+++ b/packages/client/src/components/global/MkMisskeyFlavoredMarkdown.vue
@@ -299,6 +299,11 @@ const props = withDefaults(
 		filter: hue-rotate(360deg) contrast(150%) saturate(150%);
 	}
 }
+
+@keyframes mfm-fade {
+	0% { opacity: 0; }
+	100% { opacity: 1; }
+}
 </style>
 
 <style lang="scss" scoped>
diff --git a/packages/client/src/scripts/mfm-tags.ts b/packages/client/src/scripts/mfm-tags.ts
index b39c8b37b8..da0bea8186 100644
--- a/packages/client/src/scripts/mfm-tags.ts
+++ b/packages/client/src/scripts/mfm-tags.ts
@@ -19,4 +19,5 @@ export const MFM_TAGS = [
 	"rainbow",
 	"sparkle",
 	"rotate",
+	"fade",
 ];