Rin's second cousin once removed, and her guardian. He shares an exceptionally close bond with Rin, akin to that of a father and daughter or siblings.
For a brief period, he was in love with Rin's mother, his cousin Aki, before she passed away. Following her death, he officially became Rin's guardian.
He is fiercely protective of Rin and harbors a strong dislike for Aoki due to Rin's affection towards him, which makes Reiji extremely jealous.
As the story unfolds, it becomes evident that his inability to fully come to terms with his lover's death has led him to project his feelings for her onto her daughter. He has convinced himself that Rin will take Aki's place once she reaches adulthood.
