Kumanaku is a troop member of the 1st Division of Shinsengumi, led by Captain Okita Sougo.
Already well-known among the ranks as a cleanliness freak, he observed that the toilets in the headquarters are really filthy and that it was a result of ill-discipline among troop members. He made a fervent plea for a complete overhaul of mindset, even going up to Hijikata Toushirou with his proposal for a Toilet Revolution. Hijikata was bought over by his plan and the 3 of them, Hijikata, Okita and Kumanaku tried various plans to get troop members to adopt more hygienic toilet habits. Thereafter the scheme merged with Hijikata's dream, which was a parody of Miyazaki Hayao's animated film, Nausicaa.
He has mole on his forehead, until Okita scrubbed it off with a toilet brush. His mole was subsequently used by Okita as a target point on the urinal to get troops members to aim their pee more accurately.