After the destruction of the earth, human civilization wandered among the stars. Zheng Yi, who is only eighteen years old, looks like a cute boy that everyone loves - round almond eyes, fair baby face, two small dimples when he smiles, and a milky voice when he talks. He is the "little puppy" that everyone on the Star Wandering Fleet loves. However, no one knew that beneath this innocent and harmless appearance, there was a heart colder than steel.
Zheng Yi was once the top but most secretive killer in the Federation, codenamed "Zero". His life creed is simple: complete tasks, receive rewards, and support himself and his sister. But a conspiracy caused him to lose his only relative, and also made him discover that the universe was being secretly eroded by an evil force. Many of the seemingly normal senior officials of the Interstellar Federation have long been possessed by mysterious demons.
The ideal peaceful world has never existed. The reality is a huge web woven by demons. Zheng Yi took the last holographic image left by his sister and embarked on a lonely journey across the galaxy. His goal: to find the source of the demon, avenge his sister, and find an answer for himself - in this universe where demons are rampant, can a killing machine survive as a human being?
On the way, he obtained the "Star Spirit System" from ancient civilization. This golden finger allowed him to absorb the energy of demons and continuously evolve. But every time he uses it, his humanity will be eroded. When the murderous intention hidden under the puppy's appearance is fully awakened, the entire galaxy will tremble.
