He is voiced by Yoshitsugu Matsuoka in the Japanese dub, and by Orion Pitts in the English dub.
Yosetsu is a young man of average height, he has long black hair that is spiked upwards and wears a white headband with a blue zig-zag pattern to keep his hair out of his eyes.
His costume consists of a baggy, full bodysuit with the collar reaching above his chin as well as shoulder pads and a bag containing materials for his Quirk. In addition, he also wears a striped headband in place of his zig-zag one.
While not the most social in his class, Yosetsu is a tense and somewhat foul-mouthed individual although he apparently becomes more talkative in life-or-death situations while still retaining his harsh manner of speech. Furthermore, he is said to be proud of his Quirk and confident in it's capabilities.
Despite this however, Yosetsu does prove to be very brave and selfless, as shown when he saved Momo Yaoyorozu and carried her to safety, even with the Chainsaw Nomu in hot pursuit behind them. While showing fear during times like these, he was also willing to put his life on the line, highlighting his true bravery.
He was also willing to stand in for Itsuka Kendo and halt Neito Monoma's trash-talking of Class 1-A by whacking him with a board.
Weld: Yosetsu has the ability to fuse objects at an atomic level, but it requires him to touch them both in order for the said things to be fused together. It's very effective for both organic and inorganic.
- Yosetsu likes mobile games.
- It is revealed in the Ultra Analysis Book that Yosetsu was raised in a small town factory, and that he is skilled with support moves. It also stated that "He's kind of into Yaoyorozu", indicating that he has a crush on her.