Izuku Yagi is diagnosed as Quirkless when he was 4y/o. He was then neglected, abuse and tormented by the people he trusted every single day. When he was 14y/o, he was lying in his own blood, injured and semi-conscious. That is when [Mun Cheon, the Spear of the Black Wings] appeared before him and took him to the world of Jiang Hu.