akiyama nenehisa, tartaros online, 1girl, blue skin, colored skin, copyright name, detached sleeves, dress, fantasy, female focus, fins, green eyes, harp, head fins, instrument, long hair, lyre, mermaid, monster girl, music, musical note, no pupils, nymph, ponytail, rock, simple background, singing, siren (monster), sitting, solid eyes, solo, tail, tattoo, tiara, very long hair, very long tail, white background