1) The “Mob” in the title is a term used to refer to minor character/s or extra character/s in a series.
2) Majime-kun and Charao-kun
** Majime-kun (Mr. Serious) = someone diligent, serious and honest (at work or studies)
** Charao-kun (Mr.Playboy) = someone flashy or gaudy, likes to flirt with girls, but easy to talk to
3) Kirei-kei is a type of Japanese fashion that is beautiful and elegant
*please refer to the Notes above for the terms