Tha main story is about Haruko’s brother Taichi, who spots a suspicious girl stalking his big sister and gets to know from her that Haruko might be going out with her brother. Taichi being a siscon and Saki being a brocon, they join forces to ascertain whether their older siblings are really dating or not.

Additional content includes short comical side-stories about Misae and Touko’s relationship, Yuuhi switching places with Meiya and the following confusion of the A01 team, a contest pitting the whole team A01 against Commander Radhabinod, and everyone’s favorite hard-as-nails strategy game Akatsuki Haruka Nari 2.