You mean Eri uses Sayu
? I can't believe both times on H!M, that fact showed up. Poor Sayu
.
"Dependent" would be a more suitable word than "use" I think. Eri is like the scatterbrain and kooky one of the team so being her bff Sayu would think of looking out for her I guess. Plus Risa did mention she found Sayumi the more mature one of the 2.
Reina wearing glasses in their bus/van 
so I guess she really does wear glasses. So far it seems like Reina, Eri, and Yossie wear glasses/contacts
Could it be that Reina was messing around with someone else's glasses? Or could it be a prop? I remember seeing Gaki-san wearing glasses too in a pic with Ai and someone else (can't recall who it was) and she has perfect eyesight

Okay, I tried... don't take this too seriously, that means with a whole handful of salt (and please don't kill me) cuz I'm using a dictionery and other sources for this, and they aren't very good one I might add. These are from the charts Ren posted earlier.
- Reina ---> Koha = kirarin-chan (maybe Reina likes Koha in Kirari mode?)
- Reina ---> Aika = Aika-chan (she calls her that?)
- Risa ---> Miki = enemy type feeling (maybe Risa can't stand Miki being so close to her Ai

)
- Risa ---> Aika = teacher (or wanna be her teacher)
- Eri ---> Reina = rabu (does rabu mean love?)
- Ai ---> Yossi = trust
- Koharu ---> Sayu = stepping stone
- Koharu ---> Reina = looks to her (looks up to her?)
- Koharu ---> Miki = use
- Koharu ---> Aika = rival
- Yossi ---> Koha = protector
- Yossi ---> Ai = a little heart something (I guess Ai makes her heart go a lil faster?)
- Yossi ---> Reina = a leader's duty
- Miki ---> Risa/Reina/Aika = doesn't see them
No idea what the green double-headed arrows mean. And let me say again, this might not be totally accurate, if even, so please don't kill me *begs*