Yosetsu Awase studied in Class 1-B at U.A. High School, wielding the "Weld" Quirk. This power enables him to fuse objects together upon contact, effectively restraining opponents by binding them to structures or repairing damaged items in combat. He demonstrated early combat proficiency during the U.A. Entrance Exam, ranking 10th overall with 50 villain points and six rescue points. His practical skills continued to show in the U.A. Sports Festival, finishing the Obstacle Race in 12th place. He formed a cavalry team with Tetsutetsu Tetsutetsu, Juzo Honenuki, and Ibara Shiozaki. While their team failed to advance, he supported Tetsutetsu and Ibara accepting tournament spots offered by Itsuka Kendo. During the Forest Training Camp villain attack, Awase encountered Momo Yaoyorozu. After a Chainsaw Nomu injured her, he carried her to safety while evading the creature. When the Nomu retreated, he welded the tracking device Momo created onto its back, facilitating the creature's later location. In the Joint Training Battle against Class 1-A, he teamed with Setsuna Tokage, Kojiro Bondo, and Togaru Kamakiri. During the fourth match, he ambushed Katsuki Bakugo using stealth and his "Construction-Done-Kwik: Weldcraft" move, welding Bakugo to a pole. Rikido Sato freed Bakugo, however, leading to Awase's capture and his team's defeat. Personality-wise, Awase is often tense and foul-mouthed casually but becomes sharply focused in life-or-death situations. He displays selflessness, refusing to abandon Momo despite the risk. He holds pride in his Quirk and practical abilities, compensating for average academic performance with high combat technique, and does not engage deeply in inter-class rivalries, apologizing for Neito Monoma's behavior toward Class 1-A. Statistically, his capabilities are balanced: power (2/6), speed (4/6), technique (5/6), wits (4/6), and staying power (4/6). His hero costume incorporates steel logs for long-distance binding and layered shields for defense. Post-U.A., Awase graduated and became a professional hero. Eight years after the Final War, he remains active in the hero industry.