First Manga Appearance: Chapter 133
Name Meaning: Mau=to dance, Chi=blood; earth; milk
Gangs: Yokohama Calvary
Transportation: Chevrolet Camaro
Notable Features: Wears a surgical mask; has facial scars hidden under the mask; not very talkative; one of the 18 elite hit artists from the Yokohama mob
Member of the mob gang known as the Yokohama Calvary. He was hired by some Vebejail band members, along with 18 other hit artists, under the "Death Demon" contract, to kill Natsu. However, after playing around with Natsu, Natsu turned the tables around & started killing them one by one. He gets run over but is seemingly unaffected. Scared, one of the mobsters accelerates the car & plunges into the ocean along with Natsu. Of the 18 hit artists, only Mauchi & Nakagaki survive, although severely scarred & Natsu is presumed dead.
Reappearing years later with Nakagaki as one of the Yokohama Calvary's leaders, he begins an assault on Shonan simply to prove that his Yokohama gang is tougher than Shonan gangs. He & Nakagaki single-handedly take on a restaurant full of Enoshima students, beating them down. They proceed to search for the strongest fighter in Shonan, attacking Enoshima students & interrupt a fight between Katsuyuki & Tamura, beating both men down with ease.
They are confronted by Enoshima's leader, Nakajo Kunito. Mauchi gets knocked down by Nakajo, who gets attacked from behind by Nakagaki. He & Nakagaki set their eyes on the Oni-baku & run into Saejima, whom they beat up. They drag a bloody Saejima back to Ryuji's bus & holds Nagisa hostage. They ambush Ryuji as he returns home & rounds up their Yokohama Calvary to take out the Oni-baku.
To their surprise, Ryuji is saved by Natsu, who has come to finish them off. Eikichi & the Oni-baku Gumi arrive to aid Ryuji & he states that they are still no match for Yokohama's sheer numbers. They are interrupted by Nakajo, who has rounded up Shonan's gangs & a battle between Shonan & Yokohama ensues. They temporarily withdraw after the police arrive to break up the fight.
Back in Yokohama, their gang is attacked by Kamata, who they kidnap using dirty tactics, seeing it as an opportunity to take out Natsu as well as the Oni-baku. They confront Natsu & threaten to throw Kamata off a building but to their surprise, Natsu declares that he doesn't have any friends. They contact the Oni-baku & demand them to come to the Honmoku MS Storage alone, using Kamata's safety as leverage.
Planning an ambush, they are taken by surprise when the Oni-baku single-handedly arrive on a rampage & take out most of their men. Mauchi fights Ryuji while Nakagaki fights Eikichi. Kamata breaks free & attacks Mauchi, but is knocked into a car & driven off the ledge. The car is stopped by Natsu, who arrives to save Kamata & Nakagaki shoots Natsu from behind, killing him. After Nakagaki gets beaten down by Eikichi, a petrified Mauchi declares that he knew nothing about the gun & is beaten down by Kamata.