A highly detailed anime illustration of a young woman with short purple hair, blunt bangs, and sharp light purple eyes, serious expression, standing dynamically in a shallow underground river inside a cavern. She is wearing a tight navy blue one-piece school swimsuit with white "Erika" text on the chest and a small "U" logo on the hip, emphasizing her athletic figure. In her right hand, she holds a large ornate double-bladed battle axe over her shoulder, the axe featuring intricate silver and gold designs with embedded glowing blue crystals. Her left hand is extended forward, summoning swirling water magic effects with splashes and droplets in the air. The background shows rocky cave walls with a dramatic sunset glow streaming in from an opening, reflecting on the rippling water surface at her feet. Epic fantasy atmosphere, high contrast lighting, vibrant colors, water particles, dynamic pose, masterpiece, best quality, by professional anime artist.