Rainbow Clay Anime Girl Portrait

Create a clean vertical 2:3 portrait illustration of a stylized 3D anime girl bust on a pure white background, rendered like smooth clay or soft vinyl with a luminous rainbow gradient material. The character, {argument name="character name" default="Oyagi"}, is shown from the chest up in a three-quarter pose facing left, with her head turned slightly toward the viewer and a calm, distant, expressionless mood. She has a doll-like face with simplified features, blank almond-shaped eyes without pupils, a small nose, and small closed lips. Her hair is composed of exactly 6 large rounded floppy segments: one long segment falling down the left side, one large bang sweeping over the forehead, one smaller rounded bang on the upper right, one back crown segment behind the head, one right-side vertical segment, and one far-right tapered segment. She wears a simple short-sleeve T-shirt with one prominent rolled sleeve visible in the foreground, rounded shoulders, and soft sculptural folds. Apply a seamless iridescent pastel rainbow gradient across the entire figure, blending hot pink, coral, orange, yellow, mint green, cyan, blue, violet, and magenta, with gentle subsurface-like lighting and no hard outlines. Use soft studio lighting, smooth shadows, high-resolution 3D render quality, centered composition with generous white negative space. Add a small handwritten signature and date in the bottom-right corner reading {argument name="date text" default="July 28, 2026"} above {argument name="signature text" default="Oyagi"}. Avoid extra objects, scenery, borders, or watermarks beyond the date and signature.