From designer's website:
A Roleplaying Game About
The Cute, Disturbing Adventures
Of Cute, Disturbed Little Girls
Mascot-tan is a weird little RPG where the players take on the roles of anime/manga mascot girls, in the vein of Habanero-tan and the OS Girls, and have wacky little adventures. The game's rules are pretty simple, and intended to help promote an atmosphere of chaos and abuse appropriate to the genre. Action resolution is also handled by playing Janken (Paper-Rock-Scissors), though you could be boring and use six-sided dice instead if you want.
Mascot-tan also introduces the RPG Girls, mascot girls for four of the major RPG systems (as well as one for Mascot-tan itself). Be afraid.