Yasuhiro, the protagonist, becomes a shut-in after witnessing his parents' violent marital fights. His father is selfish and unfaithful, while his mother, Chisato Shoda, suffers abuse at his hands. When Yasuhiro sees his mother being assaulted, he desperately hugs and tries to protect her. Yet in that moment, he feels his penis erecting involuntarily, beginning to perceive his own mother as a woman. Realizing he may have inherited his father's lecherous nature, he sinks into deep inner turmoil. Three months into his reclusive life, signs of change begin to emerge.