The Villain's Self-Development Manual

Oh! It's over! Unexpectedly, the drama of time travel also fell on the "author". Others think that time travel is a happy thing - having a beautiful woman in your arms, being slapped in the face with a golden finger, and even if it doesn't work, you can still have the status of "grandson of a wise man" or "ancestor of the reincarnated devil king"! Why has the author time-traveled into the body of a villain! Making trouble? Short-lived? …