The Protagonist's Party is Too Diligent - Chapter 4

A back-to-basics(?) monster evolution novel.

After spending his sixth year at Hogwarts a century ago, Harry finds himself back in the cupboard under the stairs in 1991, once again receiving his Hogwarts acceptance letter.“You’re telling me my parents were killed by a dark wizard?” Harry asked. “Who is this dark wizard? Why are you all so afraid of him that you won’t even say his name?”“It’s Vol—,” Hagrid began cautiously. “Well, we call him Voldemort, because he personally killed hundreds of people.”Harry nodded nonchalantly.“And what happened the next day?”Hagrid: “Uh?”--

I possessed a reliant villain who was in debt and clinging to the heroines.“Why did I give all these good things to others?”From now on, I will solely focus on my own growth.After stopping these villainous acts,the heroines’ reactions were strange.

A biker tries to save a cat on the highway and gets hit by a truck (Truck-Kun), he was rushed to the hospital but, due to internal bleeding, he dies only to be reborn as a cat, in a new world with a system.

In this new and vast world, he tries his best to get used to his new body and get stronger along the way. With his overpowered system and skills. To one day become untouchable.