Mustard/Synopsis

Vs. Hero Killer Arc
During the aftermath of Hero Killer: Stain, Mustard is inspired to move towards the League of Villains.

Forest Training Camp Arc
Mustard joins the League of Villain's Vanguard Action Squad following the Hero Killer's defeat. While the team waits in a warehouse to be dispatched on their first mission, Muscular mentions that they need to hurry because he is ready to fight. Unmasked, Mustard replies that they have been ordered to wait and must refrain from doing anything to stand out.

Most of the Vanguard Action Squad arrives at the Wild, Wild Pussycats' Beast's Forest reserve and observes the U.A. High School students training there. Himiko Toga complains about the style of her new gear and Mustard tells her to worry about its functionality, not it’s fashion. The next night, the mission to capture Katsuki Bakugo commences. Mustard fills a large area within the forest with the poison gas produced by his Quirk. Juzo Honenuki is one of many students knocked out by the gas.

Mustard feels the presence of two people approaching him as they rush through the typhoon of gas he has created. Impressed the students have located him, Mustard reaches into the folds of his uniform and says he expects no less from U.A. students. Otherwise unconcerned, Mustard pulls out a handgun and says that no matter their Quirks, the students are only human. Tetsutetsu Tetsutetsu suddenly comes charging through the gas and Mustard counters by swiftly shooting Tetsutetsu's gas mask off his face.

Mustard recognizes him from the U.A. Sports Festival and remembers his Quirk transforms his skin into steel, making him bulletproof. Even so, Tetsutetsu can only go for as long as he can hold his breath while inside the field of toxic gas. Tetsutetsu tries to rush an attack, but Mustard punishes him by shooting him an