Kasuga Serina, a second-year Kashima School student, stands 158 cm tall with a slim frame, pale skin, and striking pink eyes. Her shoulder-length pink hair is swept into a ponytail, spiky bangs framing her face, often accessorized with a ribbon hair tie and cross necklace. She favors school uniforms, kimonos, casual shirts, and swimsuits, her 82-53-80 cm figure fitting a B-cup.

Energetic and carefree, she charges through life with altruistic fervor and a hotblooded, short-tempered streak. As founder of the Kasuga Independent Gang, she confronts problems head-on, despising ambiguity. Childhood friends Teppei and Tatsuya join her in frequent arcade gaming marathons, though her trivia prowess falters in academic settings.

Her passions include cooking, painting, shopping, and sarcastically teasing others. Initially dismissive of romance, she pivots upon meeting aloof transfer student Yukimura Yukinojo, relentlessly pursuing his trust. This determination mirrors her habit of internalizing challenges while steadfastly aiding others.

Featured as a protagonist in *Ashita no Yukinojou*, its sequel *Masaru: Ashita no Yukinojou 2*, and *Elf All Stars Datsui Jan 3*, she anchors narratives as a loyal classmate and childhood friend, navigating school dynamics and bonds with unyielding resolve.