It's a demon. So what is the introduction?

When Qiu was seventeen years old, he suddenly broke into a strange girl named Tong Yiqing at a grand birthday dinner prepared for him by his family. The sudden appearance of this unidentified woman caused a ripple in the Qiu family, which seemed to be as calm as water. The fortune-teller said that she did not belong to this world. Eun-Hek's girlfriend Yahui sees her as a thorn in her side. The "first lover" who died halfway when love was strong made Yuan Bin even more confused. There is even a mysterious person who reported to the Qiu family that one night I saw Tong Yiqing, the girlfriend of the Tianxi consortium gentleman, appearing in the night in the city ... Is there a big secret behind this seemingly happy story? What kind of woman is Tong Yiqing? Is she the apprentice of the legendary mysterious fairy who robs the rich and helps the poor? Or an ordinary girl who really loves Yuan Bin? The modern romantic and magical romance story "What if it's a demon" reveals the answer for you.