Using a game by Alice Soft.

Kyouya is really a teacher to Andrude Ocean School, and this is a substantial ocean city. Kyouya saved Kisaragi Miyu 36 months ago. Ever since then, she's were built with a secret yearning to him. Her twin sister, Yumi, an android made by their dead parents is helping Miyu fulfill her love, but her thought is wavering between Kyouya and her sister, since Miyu's memories are implanted in her own...

Another story that targets Kyouya but Yui, the miscroscopic sister of Masumi, have been Kyouya's first love.