The Butterfly Collector: The Red Room.

A former high school teacher Sugiura lost everything when he was caught, peeping photos of his favorite student and living a degenerate life. One day, a girl named Rumi, wearing high school uniform, appears in front of Sugiura. They are immediately drowns in lust and Rumi crashes into Sugiura's apartment. Gradually, Sugiura becomes obsessed with Rumi and tie her down. When Sugiura's dark desire to leave her in a beautiful, young appearance forever, and Rumi's deep feeling towards Sugiura crosses, they head towards a beautiful but sad ending.