Mabu Akutsu, a policeman who works at a policebox, and Reo's partner.

Spoiler

Mabu and Reo are the one responsible for murdering suspected criminals and extracting their desires, creating Kappa Zombies. He worked for the Otter Empire

Spoiler

Mabu is actually a Kappa serving the Kappa Kingdom. During the war with Otter Empire, he was gravely injured and to save him, the Otter implanted a mechanical heart that explodes if he ever uttered a word of love to Reo. This causes Reo to believe that Mabu was a copy that is devoid of emotion. He died after confronting Reo one last time, saying that he loved him, exploding his heart in the process.

Spoiler

Was brought back to life when Keppi fused with the dark kappa.