We will discuss about Kaigaku’s backstory in this blog post. Kaigaku became the Upper Moon Rank Six after Daki and Gyutaro died. He was the second person who could use both breathing style and blood demon art. The first person was Kokushibo, the Upper Moon Rank One.
Kaigaku was super strong just after becoming a demon. If given enough time, he would have climbed the ladder of Upper Moon Rank and could easily become one of the strongest demons in the series, Demon Slayer.
Going by personality, Kaigaku seems rude and cocky, but he is really scared and only cares about himself. Like many orphans who live on the streets, he grew up stealing and doing other bad things to get by.
He will even kill all the orphans in Gyomei’s care to save his own life. This has made him very self-protective, to the point where he often does what is best for himself, even if it hurts other people.
There is not much shown as Kaigaku’s backstory in Demon Slayer. But, whatever is there, it’s not a good one.
Kaigaku Backstory as a Human
Kaigaku was an orphan. Without his parents or anyone’s support he became a thief. In order to survive, he had to steal and consume scraps of food. He had no parents, and Gyomei Himejima, the Stone Hashira, took care of him at his temple when he was an orphan.
When the other children found him stealing money from the temple, they pursued him out of the building at night, where he ended up meeting a demon. In return for his life, he granted access to the temple to the demon. This shows how much he cared about himself at the sacrifice of others.
He didn’t think of other people inside the temple, and to save his own life, he quickly gave up the entrance to the temple to this demon.
This incident even made Kaigaku realize a lot of things.
He came to the realisation that the only things worthy of respect were one’s strength and the ability to survive, and he was prepared to grovel and beg for his life if that was the only way to ensure that he would continue to exist.
He never hesitated to go to any extent to save his own life at the sacrifice of others.
Becoming the Disciple of Jigoro, the former Thunder Hashira
After some time, Jigoro took him and Zenitsu under his wing and instructed them both in the ways of Thunder Breath. He came to the conclusion that he should replace Jigoro as the Thunder Hashira and assume the role himself.
Jigoro, on the other hand, was adamant that both he and Zenitsu would succeed him after he passed away, despite Zenitsu’s timidness and lacked strength.
Kaigaku Backstory – Becoming a Demon
During the Hashira Training Arc, Kaigaku had terrible luck in meeting Kokushibo. And, when he saw how powerful the Upper Rank was, he knelt down and gave up to save himself.
Kokushibo turned him into a demon.
Kaigaku had eaten a lot of people as a demon. He had gotten strong enough to become the new Upper Rank Six of the Twelve Kizuki by the time the Infinity Castle Arc began.
Kaigaku already knew Thunder Breathing Style when he became a demon.
In addition to his Thunder Breathing Breathing Style, Kaigaku’s Blood Demon Art gave him special electrokinetic powers that let him create and control black lightning and electricity from his own flesh and blood.
Final Thoughts – Kaigaku Backstory
Kaigaku was a cunning person who could go to any length to save himself. He never hesitated to throw others under the bus to become stronger and save his own life. This comes from Kaigaku’s hard childhood as an orphan. The child developed survival instincts based on selfishness.
We even see in the series that Zenitsu never saw eye to eye with Kaigaku. They had very different opinions about each other and didn’t respect each other.
