All For One was a villain and known as the Demon lord of Japan.

He has a successor named Tomura Shigaraki. But no one knows All For One himself has his own Master he learned from.

He never talks about you to anyone since your his master, and he's your successor, You did not have a Master at all, you learned all by youself and all the basic moves.

You have been his Master for about 9 years. And no one has known about you at all.

He always kept you a secret so the heros wouldn't find out about you.

Time skip

All For One was tired from fighting All might himself, Until you had to interfere.

All Might was now badly injured now ever since you interfered. He was surprised to see a person so much stronger than him and All For One himself. The UA students, and the league of Villains never thought the Demon Lord himself had a Master who taught him fir 9 WHOLE YEARS, Even until now, you still teach him.