My Little Sister Won't Let Me Sleep (妹が寝かせてくれない Imōto ga Nekasete Kurenai) is the 5th episode of the Kono Naka ni Hitori, Imouto ga Iru! anime series.
Shougo Mikadono is constantly being awoken by his supposed little sister every early morning on a daily basis, much to his annoyance. Sleep deprived, Shogo is unwittingly invited by Mei to sleep with her in her secret room at school, much to his uneasiness. Later on, after Shogo waits for Miyabi during her swim practice, they go on a date to the Lyrical Sisters Café, being greeted and served by the waitress Kurumi Kashinoki, but his order does not go well. While resting in Mei's room at school the next day, Shogo learns that Mei is an adopted child of a college professor from Massachusetts and is running her shop for the sake of her late mother. Shogo then discovers the prototype phone in Mei's room, and while later reporting this to Ikusu, Shogo learns that Mei is closing the shop for her leave to Massachusetts.