Shinomiya Kyouya is forced to become a new member of the GJ, an unidentified club that dwells in a room of the former building of a certain school. Here he meets the club leader, Mao, a short girl with a big attitude; Mao's younger sister, Megumi, who has the heart of a bipolar angel; the recognized genius with a lack of common sense, Shion; and the always-hungry and mysterious Kirara. Time flies with these unique girls around.

[Source: MyAnimeList]

It is the spring break immediately after Mao and the others graduate. It is the season of cherry blossoms, and the new school term will soon begin. One day, Kyouya is suddenly stuffed into a bag. When he is let out, the scenery he sees around him is that of New York—except the room looks exactly like the GJ Club's room.

[Source: official website]