While Airu is often seen as a cold antagonist, later parts of the series reveal that his harshness stems from a desire to protect the family after their father's death. He eventually becomes a subtle source of encouragement for Romio to grow stronger.
During a search of Romio’s room, Airu finds incriminating items, including a rosary and a brassiere, which heighten his suspicions. He threatens Romio with expulsion and banishment from the family if he is indeed betraying their house. 10 : Romio and Airu
To "straighten him out," Airu puts Romio under strict 24/7 surveillance and tutoring for an entire week. While Airu is often seen as a cold