Here’s an excellent vanilla hentai manga, made of an almost (save an unrelated last chapter) full-volume scenario, served with rather pleasant old-school art style 
The main story features a highschool girl falling in love with her young male biology teacher. Of course they end up having sex on multiple occasions, but there was a slightly realistic note here, as they didn’t rush straight into marriage twenty minutes after their eyes met.
The male teacher had reservations about taking advantage of a teenage girl’s first feelings of love. She’ll lack self-confidence, she’ll be impressed by the adult’s figure of authority, she’ll be inexperienced with controlling her emotions, taking all that into account, it’s not so surprising he would push her back…
But fear not, it’s full vanilla, it’s just there’s a proper amount of character development (you know, growing into a better person) ^^
Graphically, it felt like reading a shoujo manga, or an hentai manga released in the early 2000s. You felt the mangaka’s love for the characters, each panel felt unique, I didn’t hate it :3
Well, I hope you’ll love the read, thanks a lot to SquigglesJP! 
