Don't leap to conclusions about the age gap content-- 'Aoi-san' is short and sweet at only one volume, and a comedy 'romance' in the simplest form: after their initial misunderstanding, both of the leads are just trying their best to navigate an extremely weird situation in their own way. It's about a young girl's idea of love, having an innocent crush on an adult-- and just how uncomfortable it can be to navigate that delicate situation as the older party.
I rated this as a 7, but think I may bump it up to 8. It's brief and doesn't go anywhere crazy, but it's very earnest in its execution, and I feel like that's kind of rare to see.