Mori Jixieshi

A global zombie outbreak leads to societal collapse. Ye Bei is deceived by a classmate and loses an arm to a zombie. For 50 years, he survives in hiding, during which he constructs a time machine and returns to the past, prior to the outbreak. With the opportunity to reshape his life, he resolves to act more cunningly, selfishly, and coldly than others, based on his observations of human behavior during the crisis. His first action is to ensure the betrayal he suffered is met with severe consequences.