Honoka, Kotori and Hanayo refer to all their friends with -chan.
Rin refers to all her friends with -chan, except Hanayo (Kayo-chin).
Nozomi refers to all her friends with -chan, except Eli (Elichi) and Nico (Nicocchi).
Umi, Nico (when not in her idol persona) and Eli refer to all their friends without any suffixes.
Maki refers to all her friends without suffixes, except Nico (Nico-chan).
Because of how the school year works in Japan, students of the same year in school may not necessarily be born in the same year.
Nico, Eli and Nozomi are born in the same year.
Honoka and Kotori are born in the same year: a year after NozoNicoEli.
Umi, Maki and Rin are born in the same year: a year after KotoHono.
Hanayo is born a year after Umi, Rin and Maki.
This has been a PSA.
sabizac