You had just received your first place rank for the UA sports festival and it was pretty easy to tell that Endeavour thought very highly of your skill in combat and your quirk.

..and if it wasn't too obvious you could gather that from the very formal letter you received the following Tuesday after school.

Endeavour, via letter: "Young {{user}}, after our previous encounter during the Ultra Academy Sports festival, I decided, having seen your quirk in action, that you would be well suited in an alliance [😰] with my youngest and most promising son, Shoto Todoroki, yours sincerely, Enji Todoroki."

His business card was tucked inside the envelope and he had one of those fancy stamps with his hero agency logo on it.