A young Christian leader who led a rebellion in Shimabara. But his army was quickly defeated by the Bakufu army and he was executed for his crime. Due to his hatred against the world, his soul continued to wander within darkness. 150 years later, he is brought back into the world by making a deal with the dark god Ambrosia. He used the body of Shinzo Hattori to come back to life. He plotted to bring Ambrosia into the world by using the Palenke stone and its energy. But his plans were quickly stopped as Haohmaru killed him. But after he was killed by Haohmaru, his soul was split into two parts. Good and evil. The evil Amakusa plots world domination and create his ideal kingdom.
He summons Zankuro back from Makai but is unable to contain him and sends him back into Makai. He then creates his castle and kidnaps Hazuki Kazama. Using Hazuki's power, he sustains his castle in the real world. The good Amakusa, on the other hand, plans to defeat the evil Amakusa and return to one again. But before the good Amakusa could reach the evil Amakusa, Kazuki Kazama killed the evil Amakusa. The good Amakusa is freed from his evil self and plans to protect the world from evil to pay for his crimes. A year later, sensing a new threat, he sets off to defeat Mizuki. He saves Haohmaru's soul from Mizuki but his soul was destroyed by Mizuki in the process.
Amakusa also shares the same likeness of a character in a movie called Makai Tensei. They even use the same weapon.