Any other anime/manga nearly as good as PEAK BOX ?

I wish I've never seen the anime or read the manga until later this year or next year.
It's too good that it's addictive.
I would like to know if there is other stories with wholesome mature romance with any other setting than pure high school (mystery or sport for example) and I wouldn't mind it not being in high school setting.
This is my first time reading anything romance with mature character and no typical shounen comedy.
I consider romance the worst type of stories. Either cheesy or immature characters or boring drama.

If possible:
- No losers or overly shy characters like Honey Lemon Soda
- I wouldn't mind shoujo but I prefer shounen
- Preferably not pure romance
- Long/normal build up romance
- Wholesome story without fanservice / tsunderes (not main couple) / disturbing subjects like s.assault or bullying

Or maybe I should reread peak box for the rest of my life