In the last life, he was his fellow junior. During a sparring match, he accidentally injured him by mistake. The doctor said that he would never be able to stand up again.
He didn't believe it and searched all over the world for a good cure, but to no avail. Seeing him sitting in a wheelchair, he was heartbroken and desperate. Feeling sorry for him, he jumped off a cliff and committed suicide.
Not wanting to die in vain, he heard about a method that could cure him.
So he borrowed thirty years of his life from the King of Hell, transformed into the leader of Zelan, and poisoned the world just to heal him.