Substitute Marriage, Obsessed Love

The heroine and hero saved each other as children and exchanged tokens of affection, promising to marry when they grew up. Though they eventually wed due to family arrangements, they remained unaware of each other's true identities. Meanwhile, the hero's childhood friend, who knew about their promise, schemed to take the heroine's place by sowing discord between them. However, with the help of unexpected allies, the hero uncovered her deceit, and he and the heroine ultimately found happiness together.