Well Eri follows the "Japanese Gal" fashion as we knew from the past Dokkiri Hello Morning episode.
I'm not too sure if the first 4 pics are Eri because she looks kinda thin there but considering how "little" friends Sayu has, that could be Eri.
The 5th girl looks to be Eri though during the Kamezou days.
The 3rd picture wrote "Fuji De" (At Fuji) and we know they do go to Fuji Kyu Highland and other amusement parks on their own privately.
The last 2 are just cute and seems recent (at least within the year) as they used the pun "Dondake" which was made famous by a comedian.