A policeman who works in a kōban with Reo, his partner and lover. There is a stoic aspect to his personality where he is generally calm natured. He takes his duties seriously especially alongside Reo.
He is a kappa who once served as a knight to Keppi, but now extracts the desires of humans on behalf of the Otter Empire after being resurrected by Otter. Mabu was implanted with a mechanical heart by Otter after sacrificing himself to protect Reo, and now behaves in a cold and detached manner. Though Reo believes this is due to Mabu having to have lost his soul and personality after being resurrected, in reality, Mabu was forced to never again verbalize his love for Reo in exchange for his life. In the spin-off manga, he is the adoptive father to Sara.
