One day, high-school boy Yamada bumps into the beautiful girl Shiraishi on the stairs (literally), and their lips touch as they fall. When they regain their wits, they realize that they have swapped bodies. As time progresses, the two realize that this is not the only mysterious happening in the school.

Set in Akihabara, the shopping area has been invaded by creatures known as "Synthisters" who prey on the patrons of Akihabara, feasting on their social energy and will to live. These enemies can only be stopped by direct exposure to sunlight, meaning to defeat these synthisters their clothes need to be ripped off exposing them to sunlight.