Soushinjutsu ~P.S.＠4~

Yuuto Kiryuu is a vindictive asshole still fuming over Miono, a girl who spurned his (perverted) advances years ago. One day, he's contacted by a mysterious person (or group?), getting a little amount of a brainwashing drug he's supposed to test on Miono and her female relatives. Wasting no time on useless doubts about the reasons and the nature of this evil experiment, Yuuto immediately begins his brainwashing rampage, but he will discover soon that his mysterious 'benefactor(s)' have withheld crucial information from him...