大人だよっ！

character: mizumiya_su_\(1st_costume\). A medium shot from a slightly high angle depicts mizumiya_su_\(1st_costume\) standing in a neutral indoor space. She has long, multicolored blue and pink hair styled into twin braids adorned with bows, and vivid blue eyes. Her expression is one of intense anger, with furrowed brows and a pouting mouth. She is captured in a dynamic action, stomping her feet on the ground in a temper tantrum, with her hands clenched into tight fists by her sides. She wears her signature first costume, consisting of a blue shirt under an open white hooded jacket with an animal-themed hood resting on her shoulders. The visual style is that of a professional novel illustration and visual novel character design, featuring clean pen lines and a color sketch aesthetic. The lighting creates dense, fully rendered shadows with a high-contrast finish, emphasizing the dramatic mood of her frustration.