Ranmaru is a notorious playboy who is the only son of a wealthy family of hotel chain owners. He is extroverted, confident, and a self-professed expert of love and women, having dated many older married women. However, he has a good heart and cares for his friends and is the most active in the goal towards making Sunako into an ideal lady. He is later engaged to a reserved and sheltered girl, whose unusual attitude towards him creates mixed feelings and makes him unsure of his playboy ways.