Koushirou Saeki's upbringing with divorced parents causes him to struggle with matters of the heart. Despite having a mother and sister, it has been years since he's had contact with them, and he currently resides with his father. After a breakup leaves him feeling low, Koushirou's life takes an unexpected turn when he meets a high school student who ignites his suppressed emotions. The complication arises when he realizes that the girl he's falling for is none other than his long-lost sibling, who will move in with him and his father. However, Koushirou believes that love can flourish even in the most intricate of circumstances because of his background as a wedding planner. As he maneuvers this new reality, his heart races with excitement.