Ōtsuka grew up playing with a toy piano that her mother purchased for her, while she wrote her first song when she was five years old after listening to a nursery rhyme.
[3] In December 2014, Ōtsuka was recruited to join the Bushiroad music franchise BanG Dream!
as the guitarist Tae Hanazono; at the time, she had no voice acting or electric guitar experience.
[9][10] In late 2021, Ōtsuka and Poppin'Party bandmate Aimi conducted a series of acoustic guitar shows, called Kasumi and Tae's Stay After School Tour, with performances at Zepp's Namba, Nagoya, and Yokohama venues.
[15] Ōtsuka owns numerous pets like rabbits and birds, the former of which was adopted as a character trait for Tae.