My assumptions are :
Upper left : Tegoshi (coz it has a hand and says "Tegoshi desu")
Upper middle : ??
Upper right : ??
Lower left : Massu (coz it has a kanji for "niku" (meat) on his forehead XDD)
Lower middle : Kei-chan (coz it has narrow eyes *ROFL*)
Lower right : Shige (coz it has a mohawk hairstyle and looks old *ROFL*)
Any other opinions? XD