There he meets Professor Yannan Mo, father of Mo Cong the ML, and they're attacked by demon human head spiders and fall into the demon city. An Yin Hu protects Professor Mo throughout the ordeal. The guy leading the archaeology team lured them there intending to sacrifice them to gain immortality. Evil guy dies and An Yin Hu and Mo Yannan escape only for one last monster to pop up and attack An Yin Hu and Mo Yannan dies protecting him. Because he's last man standing, he's granted the prize of eternal youth (possibly immortality). Since he is now a teenager again he decides to look up Professor Mo's children and protect them since the professor has been divorced for years and the kids' mother abandoned the family. He uses the fake name An Jie and moves next door to the Mo family kids and finds out that the son Mo Cong (the love interest), has been lured into the mafia.

The twin daughters also have problems but are still high school students.

All three kids hate the professor because he was a spineless childish nerd.