Toyama Kasumi is the main protagonist of the BanG Dream! She is a second-year student at Hanasakigawa Girls' High School and the leader, vocalist, rhythm guitarist, and songwriter for Poppin'Party. Outside of the band, she is friends with Aya and Yukina , and, alongside Arisa , is also classmates with Misaki. Kasumi lives with her parents and has a younger sister, Asuka - whom she calls "Aa-chan" - however, it's not always clear who is the more responsible out of the two. When she was looking at the stars one night as a child, she heard a sparkling "Star Beat", and ever since that, she's been searching for it. She believes that she found it after she saw her guitar for the first time, and when she formed Poppin'Party. Kasumi has purple eyes and brown hair worn loose with segments pulled up into star-shaped buns.

While in junior high school and high school, she became part of a chorus club to help her overcome tone deafness. Euphonium 2. Her official fanclub, "Niji no Wakka", was launched on the same day.

It was released on April 5, It can be unlocked in BanG Dream! Girls Band Party!