Kasuga Souichirou

Raised by his strict grandparents as the heir to the Kasuga family, Souichirou is the rigid and serious oldest brother. He works as a surgeon for a hospital affiliated by a national university. Highly skilled in his area, great things are expected of him in the future. When he was 18, the Kasuga household collapsed. Even now, he still almost stubbornly adheres to the ancient traditions of the Kasuga family.

Because of the old Kasuga view of how "only those who are of suitable blood may join us", Souichirou is strongly against his father's desire to remarry Suzuna's mother. As a result, he openly shows his hostility even towards Suzuna. Souichirou is a perfectionist obsessed with cleanliness. He is strict with himself as well as everyone around him. Selfish and sometimes pompous, Souichirou thinks that women are "vulgar and good-for-nothing creatures."