The Real Reason Why All For One Is Obsessed With Yoichi Shigaraki

Yoichi and All For One shared the same beginning but took vastly different paths in the series. Yoichi embraced goodness, while All For One descended into villainy.. A young All For One kicking Yoichi for trying to stand in his way. Zen's younger twin brother, whom he would name Yoichi (meaning "bestow" and "one"), was the very first thing given to him in life. When they were born, Zen was forced to survive alongside Yoichi in an era of chaos caused by the uprising of Meta Abilities. The two brothers were different to the point of being polar opposites.

All For One confirmed this to be the case, stating that it absorbed and combined with the power stockpiling Quirk to make up for the strength it lacked, creating One For All. But Yoichi's Quirk supposedly lacked this due to his Quirk not being able to fully manifest due to lacking said nutrients, thus causing his weak and sickly body.. Yoichi is the only person AFO could not control or manipulate. He gave Yoichi that stockpile quirk because he manipulates people by giving them favourable quirks and expecting a favour in return. Yoichi was an exception to this and so AFO saw that stealing one for all was a method of controlling or "owning" his brother.