Karelstein Yuriy is the main character and assistant to the Hero Eristia Vitral in the RPG game Editing Another Story of Fallen Maidens: Fallen Hero and the Magic Sword of Truth.
At the beginning of the game, Yuriy is a soldier of the Order trying to stop the invasions of the succubui. After being saved from being raped by a Succubus, he offers his gratitude and service to Eristia. Together, they explore some mysterious ruins to look for the powerful artifact "The Magic Sword of Truth". Yuriy is kind and submissive, but oblivious to the failing strength of Eristia and her slow, sexual corruption. He often asks her if she needs help, not noticing her gradual usage of lewd words or her fantasies.
He is always raped by Eristia's monstrous forms before being revealed as his companion's daydreams. He himself is never affected by the sexual corruption. Only at the end of the game does he have consensual sex with the fully corrupted, Succubus form of Eristia and tells her his romantic feelings. He is then transformed into an incubus and together, the duo causes the fall of the Order and Lescatie.