I have problems with Japanese LNs where the MCs get absolute power but rarely does anything with it usually because the world is almost as laid back as he is and other than the odd corrupt noble most characters exist to be surprised and sing praises. Xianxia settings where strong eats the weak, everyone is a murderhobo, and everyone attacks the MC because he looked at them funny are settings I find myself enjoying. problem is it takes more than 100 chapters for them to get anywhere (if they are OP that is, if not it'll take longer). I want a series where a OP sensible MC that you would usually find in a Japanese LN be put in a violent unreasonable setting that you would find in a Xianxia novel.
Uh... does it count? http://www.novelupdates.com/series/douluo-dalu/ Edit : sorry it seems I wrong. So you mean OP MC that kills from the very first chapters? http://www.novelupdates.com/series/god-of-slaughter/
Evolution Theory of the Hunter Reincarnator Man.. if you want to compromise between CN and JP, I'd suggest you take a look at KR.
This maybe? I myself don't like it that much though... http://www.novelupdates.com/series/yobidasa-reta-satsuriku-sha/
There are a bunch of visual novels. A japanese high school boy is teleported to such a world during the three kingdoms war thing, but all of the heroes of that time are actually women in that parallel world. koihime musou is one such visual novel.
i have noticed this problem in alot of jp mc and not just in novels lol, i have the same exact questions that is posted as the topic funny thing is this is the reason why they should make xianxia anime ive seen a couple but none were from any good xianxia's in my opinion(sorry for being a bit off topic)