Ok so I have seen honorifics for the other seasons but not for this one so I decided to start one.

Rei: Rei-kun
Eri: Eri-san
Astra: Astra-kun
Yuujin: None
Hajime: Hajime-kun
Ai: Ai-chan

Rei - I don't think he uses honorifics for anyone. Actually, does he even say anyone else's name but Haru and Hajime?

Eri - She calls Ai 'Ai-chan' and Dokamon 'Doka-chan'. I think she also calls Hajime with 'kun'

I cannot recall any of the others which is weird. But what do these honorifics mean? Do they define how close they are as friends?