Bokura No Negai
No actual blood relations are coupling up so no direct incest either :) should be read after Mankai Darling as the crossover characters play more than a guest role. Had to wait till the very last chapters for the 2 couples to actually do it.
Mad Cinderella
Wakabaryou de, Kimi to
The smut scenes (which were very few and only with 3rd couple) were super glossed over and brief, or just spoken about but the all 3 intertwining stories and pairings were adorable. 3 couples short stories with 2 out of the 3 feeling kinda unfinished and leaving me wanting to read more :(
Ze Fan Book
Porno SuperStar
Has spinoff story called Shiny Star about secondary character
Kokoro (kanda neko)
Always love this mangaka's work. Ch15 & 16 side story was also awesome. Ch17 oneshot was cute too with petting scenes no smut. Skimmed through ch18 (no smut). Loved and enjoyed ch19 oneshot (cute smut, both virgins).
My Honey Express