He is cat with dark red or red fur and black eye with yellow.
Back in the Edo Era, he and Toramaru posed as neighborhood kids and made mischief. Those who were being plagued by the Bakenekos erected a small miracle-working shrine and put their favorite food within it to lure them in and seal them.
4 elementary school boys came across the shrine, and 2 of them Taichi and Hiroshi argued over what animal ghost was inside of it and ended up busting it to check, which allowed the two Bakenekos to be freed and imprison the 4 boys in the shrine. Akamaru took the appearance of Taichi and would live in his house.
He reveals his imposture when Toramaru, who impersonated Hiroshi, joins him after being exposed by Rinne, and the 2 Bakanekos show their true forms when Rokumon tried to stop them in his giant form and easily dispatch him. Upon learning from Sakura that the 2 Bakenekos must return to the shrine to set the boys free, Rinne uses his broken scythe as a play toy to lure them back to the shrine.
- His name means "Red Circle".
- They get a longer role in the anime with a Cat-Eared Damashigami, and they pass on peacefully thanks to Tsubasa.