Koki Tanaka, a former member of boy band KAT-TUN, has been arrested on suspicion of possessing marijuana, the Metropolitan Police Department said Thursday.

Tanaka, 31, was arrested Wednesday evening in Tokyo's Shibuya Ward, where he had a small portion of the drug in his car, the police said, adding that he denied the allegation and said the pot didn't wasn't his.

Tanaka was one of the members of KAT-TUN, which formed in 2001 and made its major Japanese label debut in 2006. He had made several movie, TV and stage appearances before his management office, Johnny & Associates, terminated his contract in 2013 for repeated violations of internal rules.

After leaving Kat-tun, he became a vocalist in another band.

On Wednesday, police officers patrolling the Shibuya district questioned Tanaka in the course of their official duties and found marijuana and smoking paraphernalia between the driver and passenger seats of his car, the police said.