The Girl I Saved on the Train Turned Out to Be My Childhood Friend, Vol. 9 (manga) — Kennoji

Though the gang has decided on the lead actress for the class's indie film, there's still a script to be written! And what better way to brainstorm than a session at Ryou's house?! But when Ai finds Ryou's old notebook from when they were kids, the two uncover forgotten promises that put a whole new spin on his current relationship with Hina. Unable to recall much from back then, Ryou begins wondering why -- and what exactly Hina had to do with it…