Yuna is a cruel geneticist and occultist who participates in horrific acts of genetic manipulation with dark magic. The cruel and inhumane experiments he conducts contrast deeply to his personality. He acts like an innocent, as though his experiments are perfectly ethical. Always claiming to be "just a scientist", Yuna is quick to back down from any physical altercations himself. However, he is cold and calculative, and should not be thought of as weak. He may only act weak in order to escape his would-be attackers, seen in-game.
Yuna was meant to be killed during a boss battle in the storyline, but it was cut due to time constraints and the script was left out of the final product. However in the bad ending of Breath of Fire IV Yuna dies along with every living person of the world.