diff --git a/25.md b/25.md
index 855f331c..7a612a14 100644
--- a/25.md
+++ b/25.md
@@ -47,3 +47,25 @@ func make_like_event(pubkey: String, privkey: String, liked: NostrEvent) -> Nost
     ev.sign(privkey: privkey)
     return ev
 }
+```
+
+Custom Emoji Reaction
+---------------------
+
+The client may specify a custom emoji ([NIP-30](30.md)) `:shortcode` in the
+reaction content. The client should refer to the emoji tag and render the
+content as an emoji if shortcode is specified.
+
+```json
+{
+  "kind": 7,
+  "content": ":soapbox:",
+  "tags": [
+    ["emoji", "soapbox", "https://gleasonator.com/emoji/Gleasonator/soapbox.png"]
+  ],
+  "pubkey": "79c2cae114ea28a981e7559b4fe7854a473521a8d22a66bbab9fa248eb820ff6",
+  "created_at": 1682790000
+}
+```
+
+The content can be set only one `:shortcode:`. And emoji tag should be one.