The accident occurred around 9.30pm on Aug 14 when a car with three Thais hit two student cyclists at an intersection in Chiba province.
An 18-year-old student died at the scene while a 20-year-old female student was in critical condition.
Japanese police detained the three Thais, one of whom was a woman. Blood tests on all of them showed high alcohol levels.
The police did not disclose their names.
The three Thais were charged with careless driving causing death or injury to others and driving without a licence. They denied the charges.
The accident has sparked debates in both Thai and Japanese social media. Some Japanese reportedly suggested their government scrap the free visa entry privilege currently granted to Thai travellers.