**Core settings:**
- **The heroine Ah Ying**: A firefly demon who was born in the most foul grass and possesses the power of "source light". Being able to weave dreams and heal souls comes at the cost of suffering the pain of others.
- **World view**: In the end of the Dharma era, the fog of sorrow fills the air, and the "broken heart mirror" pollutes the earth's veins and triggers the heart-eating demonic calamity.
- **Male Protagonist Shuo Feng**: A swordsman who is haunted by inner demons, bears the blood feud of his master, and forms a "heart-sword contract" with A-ying - the heart-gnawing pain is doubled, and the soul is locked for eternal life.
**Main line:**
1. **Firefly's First Light**: Aying was forced to leave her birthplace, Qianmengze, and step into a world distorted by the heart epidemic.
2. **Blood Swords on the Same Journey**: After rescuing the out-of-control Shuo Feng, the two are involved in the eternal grudge between Yinghuo Immortal Lord and Nightmare Po, revealing that "rotten grass turns into fireflies" is actually a tragic wish to fight against evil calamity.
3. **Same Heart Devouring**: In order to break the confusing heart mirror, Shuofeng burned his life to protect Aying. Aying introduced the evil spirit into his body and used his soul as a contract to exchange his vitality. From then on, the pain was connected, and life and death were in the same shackles.
4. **Eternal Night Lamp**: Nightmare uses the Evernight City to refine the demon fetus, Ah Ying breaks her jade into hundreds of billions of pure fireflies and burns her demonic body, Shuo Feng burns her remaining body into a glass heart lamp, and brings her final firefly back home.
