Noboru crossed the line with his sister-in-law, Rin. It all started when his wife ran away from home. After a fight with his wife, he was having a lonely drink when Rin suddenly showed up to visit him. She said she had come to help Noboru, who was having trouble with the unfamiliar housework. Believing her words, he fell right into her trap. When Noboru found out that Rin's true purpose was to release her sexual frustration, he used all his reason to try to run away, but his reason began to waver as Rin refused to give up and continued to seduce him.