Formerly, Kazuyuki, Fumio, and Sara taught together at a rural school. When a transfer to Tokyo was proposed, Fumio, concerned about Kazuyuki—who was struggling due to his father's illness—volunteered to take the position instead. As a result, Kazuyuki declined the transfer and married Sara. Since then, he lost contact with Fumio. Recently, they reconnected and learned Fumio had resigned due to poor health. Out of kindness, Kazuyuki and Sara invited Fumio to stay at their home. When Kazuyuki was away, Fumio took advantage and pressured Sara. Once someone to whom she owed gratitude, Sara found herself unable to resist him...