Genbu was the first of the great Saint Beasts of Maze Castle.
Kurama was the one who stepped up to fight him. To be honest, he was the best equipped to fight him.
Being able to swim through stone was pretty terrifying if you think about it.
Even a master fighter like Kurama had his trouble.
He managed to get a major wound on Kurama.
Kurama found his special stone that controlled most of his body’s subconscious thinking.
Leading to a very hilarious rearranging of his body.
And destruction. I always have fun watching that battle.