He was a good shinobi once considered to be Hanzō's equal. However, due to his fanatical view of Akunin genocide, he was exiled from the shinobi world.
Very little is seen of Kurokage in the games. Based on what is shown and what is said of him, it can be determined that Kurokage is a very old man; likely to be around the age of Hanzō as the two were rivals in their youth. Additionally one of his most noted features is that his face and body are littered with scars. His attire seems to consist of a traditional black Japanese hakama and matching robe.
While viewed as notorious for his fanatical extermination of all things evil and evil-related, Kurokage was in all actuality a righteous and just individual. He cared for the peace and happiness of humanity and believed that evil stands in the way of that. However, his black and white approach to life is the very reason why he was exiled from the shinobi world.
Later in his life, after taking in Yumi and the other Gessen girls, his desire to crush evil had subsided and all he wanted what was best for the girls whom he had been caring for. This shows his caring and genuine nature, as he was concerned that the girls would follow the same hateful, and genocidal path as he once did; a path he did not want for them to walk on.
Kurokage used to be best friends with Hanzo. In his younger days, he was the complete opposite of Hanzo and believed that shinobi had to be alone. It was possible that because they were so different that they became such good friends. However, they could never agree on the subject of evil.
Kurokage's parents were killed by evil shinobi, so he felt as though all evil shinobi were his enemies and needed to be wiped out for good. Despite Hanzo's words, Kurokage was determined to make a world where only light existed. This led to the two friends going their separate ways
Ironically, Kurokage became a renegade, detested and hated by his peers, while Hanzo became a legendary good shinobi, respected and revered. This is when Kurokage realized his ideal was nothing but an illusion. He accepted that Hanzo was right.
Around the time that he had no idea what he should live for, he met Yumi and the others. When he started living with them, his life changed completely. To him, Yumi and the others were a world without darkness. He believed that if they grew up with him, they would learn how meaningless it was to get caught up in grudges. Unfortunately, things didn't go as well as he had hoped.
Yumi and the others felt as if they owed it to Kurokage to carry out his old dream, much to his dismay. He requested that Hanzo look after them and show them how meaningless it was to fight for grudges in his place right before his death.
Gessen Girls' Academy
During Gessen's story in Shinovi Versus, Kurokage's spirit watches over Yumi and the other Gessen members as he recalls the various events of his life up until his death. He expresses his lamentation of the fact that they're following in his footsteps and trying to rid the world of evil shinobi by any means necessary and wishes only for their smiles and overall happiness more than anything else.
By the end of the story, Yumi wonders if Kurokage could ever forgive her for going against his teachings regarding evil shinobi. Unbeknownst to Yumi, Kurokage is more than happy with her decision and can finally rest in peace knowing Yumi and the others have chosen their own path of the shinobi.
Hanzo National Academy
At the end of Hanzo's story, Kurokage appears to stop a weakened Yumi from trying to continue her fight with Asuka. When he appears, Hanzo tells him that he won the bet they made when they were younger; to create a world where evil doesn't exist. He is confused at first but immediately sees that he is referring to Yumi and the rest of the Gessen elite who fought valiantly in his name to create his dream world where only good existed.
When the Gessen students arrive at the island where the Kagura Millenium Festival is taking place, Yumi and the others sense Kurokage's presence but have no idea where is. The girls search everywhere and eventually find his resurrected spirit.
Overjoyed, they all share their experiences with him and everything that they learned after his death. Kurokage beckons the girls to show him their growth, so they all head out to do just that.
As Kurokage's time is nearing its end, he visits each of the girls individually to receive his own form of closure by telling them all the things he wanted to say before he passed on. The last person he pays a visit to is Yumi.
Kurokage and Yumi have their first "beauty of death" and engage in an intense battle. Yumi emerges victorious through it all and Kurokage praises her skill and strength. He then proceeds to talk about his and Hanzo's philosophies on justice and says that they are akin to the sun and moon and have ultimately passed those views on to their granddaughters.
He tells Yumi to become a beautiful moon for everyone to see before his body begins to fade away and he passes on.
- (To child Yumi) "Some problems can't be solved with raw power, no matter how much of it you have."
- (To child Yumi) "Even with all this power, some things are beyond my control. For one thing...I was never able to meet you."
- (To child Yumi) "Power doesn't always make things right. If someone gains power without understanding that...he'll end up like me for sure."