[2] She was the girls' singles Under-17 champion of 2017 Singapore Youth International Series beating Peeraya Khantaruangsakul of Thailand.

In 2019, she reached the final of Dutch Junior International where she earned second best position after losing to China's Han Qianxi.

She lost another final at the India Junior International event to Thai player Benyapa Aimsaard.

She defeated Thailand's Phittayaporn Chaiwan in semifinal, who was a top seeded player in 2 straight games.

[4] Gunji was selected as a member of the 2025 Japan National Team, coached by Takako Ida and Shōji Satō.