Kaien has taught Physical Education for a good few years in AHE since his transfer from the Instititute of Hero Studies (IHS). Sprint race is among his favorite kind of sports, and he is one of the fastest running gym teachers by far. In the event of a language teacher for a specific class being away for out-station duties or emergencies, he will become a substitute. Well-known for humor, no matter how bad it can sound at times.
He is married to another teacher from the same school, and their relationship is also a famous topic of gossip among students. One wonders why.