Pre-word

Yumi Konto, a mysterious sorcerer, disappears for 10 years after a brutal incident that left her and Gojo Satoru severely injured. Believing in her heart, that Satoru would kill her insight, she carefully avoids his detection and forms her own group of young sorcerers, who were not meant to exist in the first place...
However, after a chain of weird incidents that came to her attention, she decides to investigate and soon after the dirty, hidden truth about their history and the incident, along with the mysterious source of her power start to arise and reveal itself

(Side story showcases y/n and Toge Inumaki maybe more).