Iruka is a pink and white dolphin. He has blue eyes and bushy black eyebrows. He wears a black tie. Due to his need for water, he's almost always seen inside an aquarium or a mobile water tank. If he's deprived of water, he'll slowly change colors until he turns black, at which point he runs the risk of dying.
Iruka is very enthusiastic about teaching, sometimes to the point of exasperating his students. His hot-blooded nature means he will push his students to the extreme and get angry at them for not listening, and he often employs corporal punishment in the form of his Dolphin Kick, though he's overall good-natured.
Iruka is the Plum class' homeroom teacher at Sunshine Academy. He has a huge crush on Jill.