Koga is known for her roles as Yuri Ashida and Juli Liszt in Aikatsu Stars!, Yuri Miyata in Two Car, Kaguya Shinomiya in Kaguya-sama: Love Is War, Shouko Komi in Komi Can't Communicate, Ange le Carré in Princess Principal: Crown Handler, and Princess Ellee/Cure Majesty in Hirogaru Sky!
[3] She was first introduced to voice acting while watching the children's television program Okaasan to Issho and becoming fond of the puppet segments featured in the show.
This inspired her desire to "become friends with dolls", which along with her interest in anime, influenced her decision to pursue a career in entertainment.
Coupled with her shy personality and difficulties expressing herself in public, she initially concealed from others her career aspiration in voice acting.
[6][7] After informing her family about her plans to pursue voice acting, Koga felt discouraged as she would require moving to Tokyo for work, which she did not view as practical at the time.
[10] She was later cast as Yuri Miyata in Two Car, where she performed the series' ending theme "Angelica Wind" together with her co-star Aimi Tanaka.
[13] She also made a cameo as a movie theater employee in the live-action film adaptation of Kaguya-sama: Love is War.