The corpse of the 49-year-old man, who had been stabbed several times in the chest and stomach, was found lying on a bed in an apartment in the west of the city, NHK reported.

The man's genitals were discovered under the bed and a blood-covered knife was also found in the room, Jiji Press said, citing police sources.

A spokeswoman for Tokyo Metropolitan Police confirmed to AFP that officers were investigating an unnatural death.