TakaraTomy have updated their website with information on the stores that will be selling the chrome Transformers Dark Side Of The Moon Mech-Tech Weapons.  The store are Toys R Us, Bic Camera and Singh Show (sharing a weapon), Yamada Denki and Yodobashi Camara (also sharing a weapon).  The fourth weapon, the silver one, I can't quite translate but it doesn't appear to be a store.  All stores will be selling the weapons on the 15th May