Kiba Kinami from the Ogami Tsumiki to Kinichijou manga series.
Trained on croppings from the Manga, kinda missing her in a school uniform, your mileage may vary.
trigger: kiba kinami, ogami tsumiki to kinichijou,
description (sports day): 1girl, blue shorts, shoes, sneakers, sleeveless, long hair, black hair, fish tail, aqua tail, aqua head fins, white t-shirt, open mouth, smile, full body, pointy ears, ponytail, aqua eyes, pointy teeth, red headband
monochrome: 1girl, shorts, shoes, sneakers, sleeveless, long hair,fish tail, head fins, t-shirt, open mouth, smile, full body, pointy ears, ponytail, pointy teeth, headband, greyscale, monochrome