She is Miyu Todo (藤堂美優), the heroine of the visual novel "I☆Can" released by LiLiM.

https://vndb.org/v2205

Her idol costume is not exactly learned.

masterpiece, best quality, absurdres, <lora:GoodHands-vanilla:1>, <lora:BetterFeet:1:1:lbw=1,1,1,1,1,1,1,1,0,0,0,1,1,1,1,0,0>, <lora:lit:0.1>, <lora:outline:0.3>

<lora:miyu_ican_test_rep8_dim32-16:1.0>, miyu, 1girl, blue eyes, pink hair, long hair, twintails, large breasts, choker, hair ornament, star hair ornament

natural lighting, soft lighting, backlighting, intricate shadow, hdr, volumetic lighting, (summer, noon, sunlight, lens flare:1.1),

(light smile:0.8), looking at viewer, (fisheye lens, dutch angle:1.1), (from below:1.2),
white bikini, outdoors, (ocean, horizon, sitting on water, wariza:1.3), (hands in water, splashing water:1.3)