A man was arrested Sunday for allegedly punching his mother in the head the previous day on her 100th birthday, leaving her in critical condition, police said.

Hiromu Nozawa, 69, is suspected of committing the assault on his mother Toshiko at their home in Kobe at around 4 a.m. on Saturday. The woman suffered an acute subdural hemorrhage and remains unconscious after the incident, the police said.

Nozawa admitted to the charge, saying he got mad when his mother demanded to go to the bathroom in a loud voice.

According to the police, the two lived together, with Nozawa taking care of his mother. He called for an ambulance on Saturday afternoon after noticing his mother's condition following the attack.