Decided to do a little research
Don't know if its right though.
Chika: There are two Chika's, one's her hairstylist, the other her make-up artist.
Koji Matsumoto: Stylist
Bancho: Probably her nail artist like ayu_ready? said.
"Junpei" might be Jun Kajiwara who plays the guitar, and "Tommy" could be Yasuyuki Tomita (A&R).