Kazuyuki, Fumio and Sara used to teach at a rural school. At the time, Kazuyuki was offered a position in Tokyo, but Fumio took over as Kazuyuki was worried about his father who had fallen ill. Kazuyuki was spared the transfer and got married to Sara. Since then, they had become estranged from Fumio, but when they contacted him after a long time, he told them that he had fallen ill and had quit his job. Kazuyuki and Sara invited Fumio to their home. Taking advantage of Kazuyuki's absence, Fumio makes advances on Sara. He is someone who once did her a favour. Sara is unable to refuse...