Nocturne of Pure Love and Cuckolding

A boy and girl who are childhood friends living in a provincial city. After graduating university, the two parted ways after swearing they would marry each other. However, their relationship crumbles due to the girl's betrayal—she falls into the clutches of a bad man from the city. Up to this point, it's a common tragedy. But— If the boy keeps his faith in love and continues to fight for the truth. If he pushes forward without hesitation, even if it means killing his own self. Then there truly exists a pure love.