I'm confused right, so did the guy die in his previous life and get resurrect as this guy? Or is it some mandella effect situation where the guy was sleeping one day and woke up in this guy's body with all his before and after memories? Every issue he's written more and more as if he's les of the former so im just curious
Basically, it is about a guy who sleeps around with women, many times older then him, and even would steel someones girlfriend (by seducing them), so that is the whole netorare thing about. The female MC was supposed to be his next target but.. he changed and one day "knew" what would happen in the future, and that he would be in a mess if he went that route... so he decide to be a "nice guy" instead.
The reason WHY he did that is the usual isekai trope, he remembers his previous life in which he read a light novel or manga that had the plot the same as this worlds.. but the originals personality seems to be non existent other then the previous change from "villian" to "nice guy" and he remembers everything from this life as well, so...
Basically, it is an isekai, but only because the author is too lazy to write character development on why this guy suddenly turned over a new leaf, and because isekai is always trending as a tag/genre. So not REALLY an isekai.