Who do the other names on the list of idols in episode 2 refer to?
Here are some likely culprits:


でんじは組 →
でんぱ組.inc, Denpagumi.inc
ワン子クラブ →
おニャン子クラブ, Onyanko Club
長森明栞 →
佐保明梨, Saho Akari
(Unsure), maybe
長森佳容, Nagamori Yoshiro,
too 
長森明菜 → 中森明菜, Akina Nakamori (singer) Credit to @Passed
Square → Circle (Unsure)