An express bus driver was arrested for driving after taking an illegal stimulant drug, the Nara Prefectural Police said.

Keita Morinaga, 49, of Naniwa Ward, Osaka, was arrested Thursday for allegedly driving a long-distance highway bus between Ichikawa, Chiba Prefecture, and Osaka from Monday night to Tuesday morning after taking an illegal drug in Chiba.

Morinaga and another driver took turns every two hours to drive the bus with 38 passengers, according to the police.

Morinaga reportedly admitted he has used "kakuseizai" (stimulants).

He was arrested on alleged violations of the Stimulants Control Law after the police found him in his car at a parking lot in Taisho Ward, Osaka, with drugs hidden inside the car, NHK reported.

The operator of the Sakura express bus, the company he works for, is located in Taisho Ward.

The company said it did not find anything unusual about Morinaga when he received a physical check immediately before he started driving. Takahito Kajimoto, head of the company's Osaka office, said he was shocked because Morinaga was a well-behaved employee. He said he will strengthen driver education.