高槻 誠一

He served Kazuki's father, former Prime Minister Tsukamoto Moritaka.

The Tsukamoto and Takatsuki families have a long relationship, with generations of politicians and secretaries on friendly terms, and Seiichi is no exception, showing great friendship and loyalty to Moritaka.

He deeply regrets that Moritaka lost his life despite being with him, and, believing that "we must protect Moritaka's son at least," he did everything in his power to secure Kazuki's release, along with his daughter Saki.

He thoroughly taught Saki about the history and relationship with the Tsukamoto family, telling her to be loyal throughout her life and to produce an heir so as not to break the relationship between the two families.