This is a world where humans need to make contracts with the undead to resist demons. The undead are divided into four levels: S, A, B, and C according to their strength. The time traveler Wang Yu attracted much attention on the contract day of Qincheng No. 1 Middle School. His soul power reached 90 points, which ranked first in the school. Previously, students either contracted C-level undead or were defeated, or obtained A-level undead like Chen Yurou. After Wang Yu opened the door to the undead, he was recognized by many S-class undead including the Bone Dragon King. However, he unexpectedly gave up the S-class and chose C-class zombies, which was questioned by the whole school. No one knows that his zombie is actually a legendary general who will kill the devil in the future.
