Warui Ko no Tame no Wasuremono TechouFundbüro der Liebe; Love and Removed Thing Left Behind; The Bad Boy's Notebook of Forgotten Things; 悪い子のためのわすれもの手帖

Story 1 - Sano tends to forget some things - a wallet, a pen. Little things. There are also things he doesn't forget - like making sure Ashihara is around to remind him when he "forgets" something. It's not deliberate. Really.