Osamake: Romcom Where the Childhood Friend Won't Lose

Kuroha's younger sisters abruptly visit Sueharu's house to tell him that she has developed amnesia. All her memories from summer break onward are gone, and they stop right when she was about to confess to Sueharu. So she suggests starting over from the moment of her own confession and erasing everything she did during the cultural festival. But Kuroha's behavior is making Shirokusa suspicious...