Kei is a young scion of a wealthy Japanese family but seems to spend most of his time jetting around Graviton City on his motorcycle. He becomes infatutated with C-ko. Little does he know, both A-ko and B-ko are vying for his attention at the same time.

Kei hardly ever speaks and has an intense fondness for Coke. In the fourth movie, his parents arrange for him to be married to Miss Ayumi, though he remains enraptured with C-ko.

In the alternate universe series, a brief scene in which Kei pursues a relationship with both A-ko and B-ko, possibly at the same time, is shown, though this is not certain, as the focus of the story shifts back to the Vs. A-ko and B-ko.