It was a fun read for sure but it got a bit bittersweet in the end. The author brought up the fact that their lifespan as human and succubus is going to be a problem in the future, and offered no happy solution so it. Kusakabe even acknowledged this and stated that Hiiragi can just find a new partner long after he's dead, which is a very realistic approach to the problem but idk, it just doesn't sit right with me.
You'd think that in a world where succubi and magic(or demon arts) exist, there isn't an deus ex that can extend Kusakabe's lifespan? Maybe it could've even been some forbidden spell that has consequences if Hiiragi used it, but it still results in them living a life together. It's just depressing to think that after a hundred years Hiiragi will end up finding another partner because it is what's natural for a succubus. Then again, I suppose something similar does happen in the real world as well with widows remarrying, BUT IT STILL LEAVES A BITTER TASTE IN MY MOUTH DAMMIT
Another thing I'm absolutely disappointed about is the fact we never got to see their children, which most likely they did have some, considering how those two are...
Oh and not to mention, we never got to know Hiiragi's true name, although cmiiw on that