marie (danmachi), dungeon ni deai wo motomeru no wa machigatteiru darou ka, artist request, official art, second-party source, 1girl, blue skin, breasts, collarbone, colored skin, convenient hair, fins, from behind, full body, green eyes, green hair, hair ornament, hair over breasts, hands up, long hair, looking at viewer, medium breasts, merfolk, merfolk out of environment, mermaid, monster girl, navel, nude, on rock, open mouth, pointy ears, shell, shell hair ornament, simple background, sitting, smile, solo, teeth, transparent background, very long hair, wet, wet hair