First it’s doukyuusei ( http://www.mangago.zone/read-manga/doukyuusei_nakamura_asumiko/) then sotsugyousei ( http://www.mangago.zone/read-manga/sotsugyousei/), and then I think there’s one with extras that’s combined with a spin-off
There's the two art books that have extras in them: Graduation Certificate and Doukyuusei & Sotsugyousei Art Book. After Sotsugyousei, there's a spinoff about a second couple called Sora to Hara. I recommend reading it or the next series, Occupation to Beloved, will probably confuse you. Once you're done with those, then you'd be ready for blanc.
And you can then pop over to the fuckyeahreaders Tumblr page to locate the "Living Together" comic they translated to heal your heart.
Oooooo I will have to check out the “living together” comic, thanks!
Which series should I read first?