Skeleton Soldier (Skeleton Soldier Couldn't Protect the Dungeon)
Recommended. Not Isekai but die and retry reincarnation type. A psychologically mature and serious webtoon. Slightly dark fantasy. I like that he is OP but still has a lot of things he can't understand or defeat. After failing to protect his mistress and being killed, Mc, a simple skeleton soldier woke up at his 1st summoned place. Back at lv1 but with all his old stats. Vowing to protect his master(s) this time, he aims to be stronger and change his destiny.
The Hero Who Seeks Revenge Shall Exterminate With Darkness
Nidome No Yuusha
Another revenge isekai! MC the summoned hero was betrayed and literally back stabbed by his "companions". On his dying breath, he swear that, if given a secound chance, he will get revenge by torturing them all and make their life hell worth than death. Then woke up back in the past, where his new life in another world started. This time, he will not "trust" those fake smiles.
Murabito desu ga Nani ka?
MC died and was reborn as a normal villager in a fantasy world. His dear childhood friends are the real deal: The hero (girl) and the sage (boy). After being betrayed by jalousy (and killed in secret) and restarting his life again, he chose to be the one protecting this time. And so began the story of the strongest Villager in the world! Boring. Typical Op Mc with boring mad in love for no reasons harem, with no personalities of course.
Dungeon Seeker