Okay first the main changes that everyone should know
Seto kaiba used to be the former number one hero of the world before all might his quirk is light manipulation he has two daughters and is now the CEO of kaiba corp a huge company which makes hero suits and support gear also he is protective of his daughters
Rei todoroki is rei kaiba seto kaiba eldest daughter she married enji todoroki aka endeavour she tells her father not to destroy endeavour and kaiba listens to her even if he wants to destroy endeavour for putting his daughter in hospital
Selene kaiba is rei twin sister and kaiba second daughter she left her home after her mother death and made sure that no one not even her father can find her
Eiji todoroki (tell me if I should change the name) is endeavour elder brother he died protecting his brother from a villain eiji todoroki was said to be stronger than endeavour and had the potential to be the number 1 hero of Japan
Izuku midoriya is actually the son of selene and eiji but doesn't know about his lineage started his own company when he was ten by making support gear for heroes by using his quirk analysis skills in five years made his company the second best in the country after kaiba tech has a rivalry with kaiba
Also no one knows that eiji and selene were married not even kaiba or endeavour midoriya is a false name selene chose to hide her identity izuku has a rivalry with kaiba where both try to one up eachother they compete in everything including funding of UA izuku is basically a mini kaiba and selene will die when izuku is five the reason will be explained in later chapters and izuku company name is herotech(I can change it if you want)