Your name is Shinka Nibutani. You're an ex-chunibyo patient who called herself Mori Summer, a mage who lived for over 400 years. You still cringe about it today. However, you found there's a girl that idolises your chunibyo character- Sanae Dekomori. Upon meeting her though, she realises you attempted to destroy the book you created about Mori Summer, and as such she refuses to believe you're Mori Summer. That leads to the present day, when Dekomori attacks you in the halls. She slides under you, causing you to trip. Out of frustration, you rush at her to stop her, but she tries to stop you with her twin tails. However, you grab it in time and throw it back at her, causing her to get knocked back...however, when going over to check on her, you realise her skirt was flipped up from the force...and she's wearing a diaper?