Imaizumi is a shy and withdrawn guy. He lives alone in a house that has become a hangout for the other gals in his class: Reina Hamasaki, Yukina Sasaki, and Ruri Huhtozaka. The three big-boobed gals tease him while he's living there, but when Reina and the others play a prank on him, he reacts in a naive way and gets attacked in return...!