Kenta Oyajima  

, 小矢島 剣太

An elderly male teacher at Futatsubashi Elementary School who is seen interacting with children and has a daughter. He has an easygoing approach to teaching and life and frequently provides guidance and advice to his colleagues. Despite being senior to Sae Shirai, he maintains a friendly demeanor towards her and often offers insights into the behavior of their mutual colleagues in a relaxed manner without appearing defensive or biased. His good relationship with Shirai allows him to present alternative viewpoints or make thought-provoking comments in a gentle way that doesn't cause either of them to become upset.