Rainbow Vinyl Anime Girl Portrait

Create a clean vertical 2:3 portrait illustration of a stylized 3D anime-inspired girl bust on a pure white background, rendered like a smooth clay/vinyl figurine with soft subsurface scattering and no outlines. The character is {argument name="character type" default="a young girl with large blank almond eyes and a calm, slightly distant expression"}, shown from the upper torso up in a three-quarter pose, body turned left while the head looks slightly back over the shoulder toward the viewer. She has rounded, plush, petal-like hair sections resembling soft floppy ears: one large oval lock draped over the forehead, two long side locks hanging down, and smaller rounded locks on the crown and right side. Her facial features are minimal and doll-like: smooth cheeks, small nose, tiny closed lips, no visible eyebrows, pupil-less eyes. She wears {argument name="outfit" default="a simple oversized short-sleeve T-shirt with thick rolled sleeves"}. Cover the entire character with a seamless iridescent rainbow gradient material, blending saturated hot pink, coral orange, lemon yellow, mint green, cyan, cobalt blue, and violet across the face, hair, shirt, and arms, with soft transitions and gentle studio lighting. Composition should crop just below the chest and upper arm, leaving generous white negative space, with the figure centered slightly left and the head near the top. Add a small handwritten-style signature and date in the bottom-right corner reading {argument name="signature text" default="Oyagi"} and {argument name="date text" default="July 28, 2026"}. Use high-resolution, polished 3D render aesthetics, matte-satin surface, pastel neon color bloom, soft shadows only, no extra objects, no border, no watermark beyond the signature.