Bleach proves the real reason Ichigo is so powerful
Ichigo's powers have always been something special, but Bleach finally gave the answer to why Ichigo's abilities are so powerful.

Warning: Spoilers for Bleach: The Thousand-Year Blood War, Episodes 12 & 13
It's clear that Ichigo is the truly outstanding soul reaper in Bleach. His strength stunned Rukia when they first met, surprising many of his enemies with unpredictable power-ups and bursts. Now, finally figuring out what makes Ichigo so special and powerful in Grim Reaper, it turns out it all has to do with his parents.
Grim Reaper fans have long known that Ichigo's father, Isshin Kurosaki, was once a Grim Reaper, which seems to be one of the reasons why Ichigo gained his Bleach powers so quickly. However, the revelation of Ichigo's mother, Masaki, in this season is also something special: she's one of the Shinigami Quincy, like Uryu, and possesses some extraordinary psychic powers. But as recent episodes have revealed, that's not the whole story of how Ichigo became and what he is.
In the two-part midseason finale of Bleach: Blood War, a series of extended flashbacks reveal how Ichigo's parents met. Isshin was fighting a dangerous, experimental Hollow when Masaki came to the rescue. Masaki lures Hollow and take it off, but not before it inflicts a severe bite on her. A few days later the bite took effect and a hollow-like hole appeared in her chest. When Ryuken Ishida, Uryu Quincy's father in Grim Reaper, rushes Masaki to his own father for help with his wounds, he is intercepted by the curious Isshin and then by Urahara, who senses the Hollowfication going on. He offers them a solution: Masaki can be saved if the power of the Soul Reaper is injected into her, shutting the void out and stabilizing her. That, of course, meant that Yixin had to give up his powers, and if it meant saving her, he was quick to agree. Isshin gets a Gigai (spare body) made from a human soul that can turn him into a soul reaper/human hybrid, locking in his powers.
Ichigo is so Powerful Because He is Bleach's Ultimate Hybrid

This means Ichigo's father was part human/part soul reaper at the time of his conception, and his mother was part Quincy/part Hollow. Ichigo inherits the characteristics of these four groups - the power of Quincy, which has just manifested; an inner hollow, which has just been discovered to form the foundation of his Zanpakuto; and Rukia's potential Soul Reaper ability that unlocks at the start of the series. Even his human genes brought something with them, as they allowed him to develop his Fullbring powers and eventually regain his Soul Reaper abilities. In short, Ichigo can draw from the power of almost any psychic race or group that appears in the series, especially because of the circumstances of his birth and who his parents were.
Grim Reaper makes Ichigo the perfect counter to the fascist Quincy Vandenreich, making him a mishmash of races. Ichigo's powers may already be incredible, but the end of the episode promises that even what's been seen in the series so far is only a fraction of what he's capable of. Ichigo and Bleach's Soul Society are going to need every drop of power they can get if they're going to defeat Yhwach and Quincy, so it's lucky he has that much to spare.
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