Keishou Abiko

He hangs around with Yuuichi and he is secretly in love with his sister, Nagisa. He realize that Nagisa yearns for his brother's love (incest) after seeing Nagisa alone in the class moaning Yuuichi's picture while masturbating. He went in to the class, which made her embarrassed, and he confessed to her and raped her out of urge. She show no resistance to him after what he said.