At least, it's not fantasy, I guess? Means, that it's not isekai, but it's still a tensei. And I bet the main attraction would be the weird interactions between the husband and his now underaged wife. Not sure if it's the right word to use, but I think youngsters would use "cringe" to describe this. I'd say the anime where grandpa and grandma turned young, was of (slightly) better taste.
