He is the second prince of the kingdom of Clarines who saved Shirayuki from becoming one of the Tanbarun's prince's concubines. Zen occasionally run away from his duties as a prince to see the rest of his kingdom, but took his duties more seriously as the story progressed. He is very close to his companions (who acts as his bodyguard), Kiki, Mitsuhide and, later in the story, Obi. Zen became immune to most poisons while he was growing up because he was given prescribed poisons.