First off, 'MegaGamers' doesnt exist. 'Gamers' is a real store chain that caters to the anime/manga crowd. There are a lot of stores in japan that cater to otaku - there are 'Animate' stores, 'Manga no Mori', etc. Good places to by software include Softmap, LLox, etc.
Megagamers is a spoof on 'gamers' in the same ilk that 'black gamers' is used in DigiCharat.