Interesting idea as a story, but I don't like how it's done. It's probably more enjoyable to others.
Reasons I dislike it:
1 I hate the strand of hair. (Minor gripe)
2 I don't like how the adventure starts.
3 It could have been done in so many other ways that'd be more.... interesting than standard op jrpg....
4 I want more cringe bone puns I mean they are just there (minor gripe)
5 slowlife, revenge, counterattack against non-undead, I revive in the future to continue the fight, isekai, I come back in the future and travel, I come back to the past as a skeleton to do what my past-self couldn't, I slowly remember my pastlife as a skeleton as I'm now invading a modern world, or even I regained my memories of a past life and now I'll finish the fight against the demon god.
See how many ideas I just listed? How many of them would you rather see over.... what we got in reality?