Yuri was born in 1890 to a Japanese father and a Russian mother.
Yuri is a Harmonixer and bears the power of fusions. Through the aid of spirits he can change his form and gain new powers. During the events of the first game, Yuri is guided by a mysterious voice, which leads him to rescue the young Alice Elliot from Roger Bacon. After the events unfold, Yuri finally confronts Roger Bacon, but not before he can summon a god to destroy the planet. Yuri stands up to this threat and kills the divine being, thus saving Earth and gaining, by some, the nickname of "Godslayer". Unfortunately, he could not prevent his love, Alice, from falling to the spirits of malice that dwelt within him.
Years later, after the death of Alice, Yuri starts living in the peaceful village of Domremy. Soon, rumours start spreading about a demon living in the village. Knowing this a Cardinal by the name Nicolai Conrad is sent there to investigate the mystery.
The Demon turns out to be Yuri, who is protecting the village from the German army. During the combat that ensues, Yuri fights Nicolai, but ends up being cursed by a magical mistletoe, for which there is no known cure. After this, Yuri ventures throughout the world, trying to find a cure for said curse and discovering that are greater evils than war looming our world.
When we first meet Yuri in Shadow Hearts, he is rather stand-offish, cold and horny. When in battle with the various hellspawn he encounters, he often insults them or makes snide remarks. For all his agression with his foes, he is incredibly loyal to his travelling companions (even if he does find some of them odd).
During the course of the game, he begins to open up with his feelings and eventually falls in love with Alice.
In Shadow Heats: Covenant, his aloof and rude traits are somewhat tempered by the loss of Alice, but he still trash-talks to his enemies and even flips-the-bird when he feels like it.
Still though, inside that hunk of flesh he calls a heart, he cares deeply for his friends and fights to protect them.