In 2016, Oshima played for the Japan U-23 national team at 2016 AFC U-23 Championship. Japan won the champions and qualified for the 2016 Summer Olympics. At 2016 Summer Olympics, he played all 3 matches as central midfielder. On September 1, 2016, he debuted for the Japan national team against United Arab Emirates at 2018 World Cup. In 2018, he participated 2018 World Cup, but he did not play in the match. He played 7 games for Japan until 2019.