(best quality,4k,highres,masterpiece:1.2),ultra-detailed,(realistic

(best quality,4k,highres,masterpiece:1.2),ultra-detailed,(realistic:1.37), 15-year-old girl with a perfect figure, don't wear anything, standing in an Onsen. The girl has a slender body, with beautiful and delicate shoulders visible. She has small, perfectly shaped breasts. The viewer can see her perfect and detailed sexual organ. The artwork should capture the realistic representation of the girl's body and the serene atmosphere of the Onsen. The lighting should be soft and highlight the girl's natural beauty. The overall color tone should be warm and inviting, enhancing the relaxing atmosphere of the Onsen,W-Sitting.