The unnamed Akuiwagumi's leader is an old Thwomp and boss of the Akuiwagumi gang in Chocolate Island in Super Mario-kun. He is a big Thwomp that, due to old age, is so blunt that he lost all of his spikes, has many upper teeth missing, and looks more like a normal and rounded rock. The word「悪」(evil) is written on his forehead.
Inspired by autumn, Yoshi's artistic side decides to carve a statue from a rock, only to be yelled by the rock itself: the Akuiwagumi's leader. At that moment, one of Bowser's Thwomps, deciding to spend his free day with his old boss, arrives and accuses Mario and his friends of hurting his boss. During the following battle, the old leader and Thwomp command the members of the gang to attack them. Occasionally, Thwomp takes the time to compliment his old boss and treat him like a retired grandfather, much to the leader's anger. In the end, Mario uses the cape to smash the Thwimps on Thwomp and the leader. The former gets his spikes broken by the hit, while the latter is spliced in many little versions of himself that start bickering on who should have the role of gang leader.