Saeki Koushirou, a wedding planner, struggles to find his own love life. Growing up as the son of a divorced couple, he has lived with his father and has rarely seen his mother or sister. After a breakup with his girlfriend, an unexpected meeting with a high‑school girl stirs new emotions within him. He soon discovers that the girl is actually his long‑lost sister, who will now be staying with him and his father. Despite the revelation, Koushirou’s feelings remain unresolved.