Tamade Chiyu from BanG Dream.
It is 100 official pictures and autotags.
Example prompt for casual ChuChu:

tamadechiyu, 1girl, solo, long hair, shorts, blue eyes, black shorts, ahoge, choker, shirt, belt, jacket, blue top, collarbone, white jacket, camisole, long sleeves, open clothes, short shorts, bangs, black rayon

School uniform ChuChu:

tamadechiyu, 1girl, solo, long hair, cat ear headphones, headphones, skirt, necktie, ahoge, striped necktie, red hair, blue eyes, plaid skirt, school uniform, open jacket, striped, plaid, shirt, looking at viewer, very long hair, blazer, white shirt, pleated skirt, celosia school uniform