Tohru-kun? It's been a while Quetzalcoatl
Quetzalcoatl (Japanese: ケツァルコアトル), or simply and commonly referred to as Lucoa (Japanese: ルコア), also known as "Fourth Dragon" ................according to Kobayashi given that Lucoa was an ex-goddess.
Unsurprisingly, she is a member of the Seven Deadly Sins and represents Lust.
Proof she is the Sin of Lust
Lucoa was once the Goddess of Wind and Wisdom, and although she's still the Goddess of Wind, she lost her wisdom due to not being pure at all; she forced $&% upon males who didn't want and/or need it.
Kobayashi, Tohru, Kanna, Fafnir, Elma, and Ilulu didn't know about it until she showed her true colors.
Lucoa is also known for posting lewd images of herself forcing $&% on men on 4chan.
She unsurprisingly joined Lord Shen and the rest of the Seven Deadly Sins.