Three Thai nationals were arrested in Japan after the car they were travelling in hit two Japanese students in Chiba prefecture, killing one student and seriously injuring the other, local media reported.
The driver faces charges of drink driving and driving without a licence.
According to Japanese media, the accident occurred on Thursday night in Choshi city around 40km east of Tokyo.
The students, a male aged 18 and a female aged 20, were struck while riding home.
The collision killed the 18-year-old high school boy at the scene and the female student is in a serious condition. Japanese media also reported that the male driver had admitted he was drunk.
Foreign Ministry spokesman Sek Wannamethee said an investigation is underway in Japan and the Thai embassy in Tokyo will provide any assistance if requested. Any help provided will be offered under Japan's laws and will take into account agreements between Thailand and Japan.