### Outline and detailed design of "Old Demon of Wannian Mountain"
#### **Starting Chapter: Traveling through another world, starting a counterattack (Chapter 1-5)**
**Core Goal**: Xu Fei survives in Wannian Mountain and finds a way to return to modern times.
**Initial Obstacle**: The old demon has a huge power and regards Xu Fei as a threat, so he sends his minions to test and suppress him.
**Hook Incident**: Xu Fei used modern firefighting knowledge to put out mountain fires, save villagers, and show his image as a "god-man".
**Initial coolness**: Modern knowledge crushes ancient crises (it's cool to pretend to be cool with knowledge).
#### **Continuation: Growth and Counterattack, Undercurrent (Chapter 6-15)**
**Growth Line**: Xu Fei learns the Wannian Mountain cultivation system, gradually masters "demon power", and unlocks modern knowledge + demon fusion skills.
**Counterattack Line**: Unite Tang Xin and Chuntao to fight against the old demon's conspiracy and expose his brutal rule.
**World view foreshadowing**: Wannian Mountain is a place of ancient seals, and the "seal" guarded by the old demon is actually a conspiracy. #### **Combined chapter: Final battle, leaving blank space for sublimation (Chapter 21-25)**
**Final battle**: Xu Fei and the demon body duel, integrating the power of the Wannian Mountain demon and modern technology, killing with one strike
