I'm not part of the downvoting crowd, but I can understand them.
The series began strongly with the premise of a post demon king world, an elf coping with the loss of her companions and discovering what humanity is all about.
And then it quickly devolved into an op character forming a party to reach the demon king castle by completing quests and fighting demons/monsters on her way. Hmm.... where have I seen this before?
And seriously, after defeating the demon king, the party disbanded because there was nothing left to do. So, we are 70 years later, but the northern territories are still prey to the remnant demon army (maybe, clean it before retiring next time, seriously, 70 years, at no point they thought that maybe it would be a good idea to use this time to clean their mess and instead of going back to their previous life?)
The characters were kind of interesting at first but now are just stereotypical, we have a cliched romance between characters that aren't even compatible...
And it keeps getting worse.
A strong start is not enough to make a story good, it's just good to get people hooked.