Early years Kojima started playing volleyball in the third grade of elementary school. She said that she was invited by a friend. She then attended
Funabashi Municipal High School. With the team, she excelled in the national tournament, such as the 2012 Inter-High School Championship. She was also selected as a member of the All-Japan High School Team. In 2013, she attended
Aoyama Gakuin University. She won the Libero Award and Rookie of the Year Award at the Kanto University Division 1 Spring League. She also selected as the member of
Japan U20 National Team and participated in
2013 FIVB Volleyball Women's U20 World Championship held in
Brno in June. She contributed to the team first runner-up in 28 years and also named as the Best Libero. She also competed in
AVC Eastern Zonal Championship in 2014 and 2016. She also selected for 2015 and 2017 FISU University Games. She performed very well in 2017 FISU held in Taipei where the team won silver medal for the first time in 11 tournaments.
Professional years On December 26, 2016,
NEC Red Rockets announced that Kojima would join the team. She was selected for the
Japan women's national volleyball team. She also selected to compete in 2022 VNL. She joined training camp for 2022 World Championship. However she wasn't selected as a member to compete in world championship. In 2022–2023 season, she helped NEC to won their first victory in six season and she won Best Receiver award. She was appointed as a captain of NEC in the
2023-24 V.League Division 1 Women's season. NEC won consecutive trophy and she was named as the Best Libero Award. On March 11, 2024, NEC announced that she would leave the team at the end of the season and transferred to
League One Volleyball in the US. In July, it was announced that she would be joining
LOVB Salt Lake. In July, it was announced that she would be competing in the
Athletes Unlimited tournament, which began in October. The tournament is a competition based on individual points. She placed 7th out of 44 players and 2nd as a Libero. She was voted as the Best Libero by the players. In April 2025, she was awarded the Libero of the Year award at the LOVB's 2025 season. == Awards ==