In 2013, Kobayashi was selected the Japan U-16 national team for 2013 AFC U-16 Championship. She scored 7 goals and became a top scorer. Japan team also won the championship. In 2014, Kobayashi was selected the Japan U-17 national team for 2014 U-17 World Cup. She played at 5 matches and scored 2 goals, and Japan won the championship.