Saeki Koushirou, a wedding planner tangled in romantic turmoil due to his turbulent past, struggles to fully embrace love. Raised in a broken home, he grapples with commitment issues. His isolated life with his father changes when a breakup prompts an unexpected meeting with a high school girl, stirring unfamiliar emotions within him. Shockingly, he discovers she is his estranged sister, set to live with them. As conflicting emotions surge within Koushirou, the complexities of family and love intertwine.