My Muscle System in the Mage World - Chapter 389 Purple Lightning

After transmigrating into a beast world, Rong Mingshi discovered that the people of this world experienced widespread mania. For example, when their emotions were abnormally agitated, they would become destructive beasts. If their emotions were abnormally low, they would shrink into their young beast form.

Zheng Tan somehow returns to the year 2003, turning into a black cat. Picked up from a rubbish heap by the Jiao family, he is given the name “Charcoal”, and so begins the life inside Professor Jiao’s family. Zheng Tan remembers that he was once a person, but currently his body is that of a cat. He has no way of speaking the human language, but can understand it, and even retains the thinking and IQ of a young 20 year old youth. Read along as he adapts to this new world, and somehow tumbles from a group brawl to catching a thief.

- Description from Novelupdates

“I can’t accept this! I can’t! Even as a ghost, I’m going to spend eternity cursing that your relationship will shatter like glass! Break apart like a pair of mandarin ducks that fly away from each other!” With such a persisting obsession, it would be difficult for the vengeful departed spirit to move on.