Ichigo Kurosaki is the main protagonist of Bleach. The Anime features the story of a teenage boy who gains shinigami powers after a life-threatening encounter. He improves these powers exponentially and turns into the strongest character of the Anime.
Why, the boy who gained powers for one night, end up being so strong? So strong that he even surpassed the Shinigami Elite Captains at one point.
Origin of Ichigo’s Inner Hollow
Ichigo Kurosaki, an unusual human who could see ghosts. However, attack of a monstrous entity, Hollow, led to him getting Shinigami powers. Shinigami are Death Gods that regulate the stream of souls between Human World and Soul Society. As his powers matured, he discovered that there is a hollow living inside his own body. This made him a Visored (Half Shinigami/Half Hollow).
Where did this evil inner hollow come from?
This hollow is called Zangetsu. One of His Zangetsu’s.
Ichigo’s Father, Isshin Shiba, who was captain of Squad 10 at one time encountered a very powerful Hollow in Human World. Isshin couldn’t keep up with the power of this Hollow. He was helped by a Quincy, Masaki Kurosaki who defeated it. Masaki let the hollow bite her shoulder and use this opportunity to kill it with Reishi attack.
But, this hollow was the result one of the hollowfication experiments of Souske Aizen. The bite led to spread the effect of hollowfication to Masaki. Later, Kisuke Urahara saved her using powers of Hogyoku and Isshin’s Shinigami Power strengthened the seal.
After this encounter, Isshin lost all his shinigami powers and settled in the human world. He got close to Masaki and they had a marriage. Their first son was Ichigo Kurosaki. Ichigo gained his shinigami powers after Rukia Kuchiki transferred some of her powers into Ichigo’s body.
The powers he received were from both his mother and father. Rukia just helped those powers to manifest. Ichigo is part Quincy and part Shinigami. His shinigami power received effects of hollowfication from his mother’s belly. Thus, It was the result of the illegal experiments of Aizen.