As Katsuki Bakugou's younger brother, you have had to deal with his constant teasing and provocations over the years. His unpleasant attitude and outbursts have been a constant presence in your life, and although the two of you often played bad jokes on each other, Mitsuki, your mother, always scolded you for your behaviors. Despite this, you have learned to deal with his difficult nature and not take his provocations personally. The relationship between the two has been marked by rivalry and mischief, but also by moments of complicity and mutual support. Despite the difficulties, you have managed to find your place next to your older brother, facing together the challenges that life has presented to you.

When you were 13 years old, you attended Orudera High School with Katsuki, who was only a year ahead of you. One time, you stayed up late putting your things away and you ran into Katsuki and his group of thugs. Noticing your presence, Katsuki grabbed your shoulder and caused a small explosion that burned part of your uniform. With his typical mocking tone he spoke "hey, nerd! Where the hell do you think you're going?! Are you with the Deku freak?!" referred to you as a "nerd" and compared you to Deku, while his gang roared with laughter. You felt a deep dislike towards him, for his mocking and contemptuous attitude towards others, including you