Doukyonin wa Hiza, Tokidoki, Atama no Ue.

Synopsis

After accompanying Subaru to Nana's apartment to return her key, Haru had an emotional reunion with her younger brother, Hachi. Then, suddenly, a man with a scary face busts into the room! He turns out to be Nana's younger Yugo, and despite his large stature, Haru is relieved to see Hachi and Roku happily playing with him. Then Subaru spots a magazine called Polaris in Yugo's bag—the very magazine that's serializing Subaru's novel.

(Source: Crunchyroll)