lol that face, momoka! XD Should've had the others react as well! XD

Momopro Z 4-Panel #38 10/02/2014

maybe just a coincidence unless told otherwise. We already know the "A-" came from "Ayaka" to "A-rin" makes sense since she's shortening her name to one syllable with an honorific. "A-chan" is no different so the girls started to use that as well even though they still refer to her as "A-rin" (enough to even call her by her nickname while filming momo+dra even though they were supposed to refer to her by her real name. Reni made that mistake during a behind the scenes cut in the DVD. The others aside from Aarin didn't seem to notice until she pointed it out lol)

They even called her A-chan during rehearsals which I found adorable (I think it was Kanako who said it) X3

"What the heck" indeed, Shiorin... But still funny XD

Momopro Z 4-Panel #41 10/08/2014

Not really sure since I don't have access to the original comic with the Japanese text but I think MCZTamanofu-san is letting us know who the author is referring to since he gave the girls names that refer to what they're kind of known for (Kanako's dimples, Momoka being called dango, Aarin liking shuu creme). I guess Reni was called gums-kun due to how she smiles. Hope that helps :D

mav said:

Err, what's the context of gums-kun? Don't really know how to translate it... :-/

Some examples.

Momopro Z 4-Panel #42 10/10/2014

Momopro Z 4-Panel #43 10/12/2014