憧れの「Y学園」に入学し、中学生になった玉田マタロウは、「YSPクラブ」に所属するジンペイたちと出会い、ドタバタながらも楽しい毎日を送っていた。ところがある日、突如巨大なサラリーマンが学園内に出現！彼は学園七不思議に認定されている“巨大サラリーマン宮沢さん”で、女子更衣室を巨大な顔で覗く変態…というウワサもあるらしい。さっそく不思議解明ミッションを開始しようとするジンペイたちだが、その様子を姫川フブキのクラスメイト・アカネが部室の外からうかがっていた。
Matarou Tamada, who entered Y-Gakuen and became a junior high school student, met Jinpei and others belonging to the "YSP Club" and had a fun life. However, one day, a huge salary man suddenly appeared in the school! He is a huge salary man, Miyazawa-san, who has been certified as a school seven wonders, metamorphosis peeping at the women's changing room with a huge face...There seems to be a rumor, too. Jinpei and others are trying to start a mysterious elucidation mission, but Fubuki Himekawa's classmate Akane was looking out for it from outside the club room.
