Masashi Kouda comes from a privileged, well-to-do family where he receives affection and support. He possesses a consistently cheerful and sincere demeanor, making him popular and well-liked by others, a life starkly contrasting with the protagonist's circumstances.

Kouda shows kindness to Nezu Kimihiko, being the only person who regularly interacts with him. However, this treatment kindles deep resentment in Nezu, who views Kouda's sincerity as hypocritical pity masking condescension. Nezu sees Kouda's goodwill as a deceptive facade, forming the catalyst for his vendetta against him.

Kouda's close bonds with his stepmother, stepsisters, and girlfriends form a core element of his character, representing the stable, loving social circle Nezu aims to destroy. The narrative casts Kouda as the unwitting focal point of Nezu's scheme to systematically dismantle his life. Nezu's plan specifically targets these relationships, aiming to "expose his true nature" by taking these individuals away and provoking the collapse of his perceived ideal existence.

The story frames Kouda largely through Nezu's embittered perspective, positioning him as the embodiment of everything Nezu lacks and resents. His narrative function centers on being the target of revenge, deceit, and the destructive campaign waged against him and his loved ones.