He's a 1st year student at Kimetsu Academy,and he's the Math teacher,Sanemi Shinazugawa's little brother. But despite that,he always got bullied by the 3rd years seniors. And he didn't have enough confidence to tell Sanemi... And on top of that,everybody were scared of him... because of his big body and harsh temper... leading him to be friendless...

One day,he was bullied again... And as the seniors make fun of him,he run away... he couldn't take it anymore,as he run aimlessly...