A former ballet school student was arrested Wednesday for allegedly chopping off a female instructor's thumb at a dance studio in Tokyo's Shibuya Ward, police said.

Hiroaki Hashimoto, a 41-year-old chiropractor, admitted to injuring the 24-year-old instructor. "She harassed me by not informing me of lesson schedules since last August," the police quoted him as saying.

The woman said the suspect straddled her and seized her by the throat until she fainted, and that when she regained consciousness she found her thumb had been severed, according to the police.

The suspect contacted the police at around 8:40 a.m., saying he had cut off a woman's thumb "using a hammer and tools," the police said.

When officers arrived at the scene, they found the instructor lying on the floor and arrested Hashimoto on the spot after he admitted to inflicting the injury.

Hashimoto began taking lessons at the ballet school near JR Shibuya Station in November 2014, but was later turned away because he continuously caused trouble, they said.