Monster Hunter 4 is the second game in the aforementioned series to be released on the Nintendo 3DS. Many updates and improvements have been made that set this sequel apart. It was released exclusively in Japan. Monster Hunter 4 saw an updated version, titled Monster Hunter 4 Ultimate (4G in Japan) released in Europe and North America. There is a stronger emphasis on platforming than previously; walls can now be climbed more fluidly and in any direction, and for the first time Hunters can grab onto monsters and attack them. Environment are larger and occupy more vertical space, and the Frenzy Virus mechanic makes many monsters more fearsome than ever. Various monsters from previous games return, most notably Rathalos, Rathian, Tigrex and Yian Kut-Ku – for a full list see MH4: Monsters. Two new weapon classes, the Insect Glaive and Charge Blade, are also introduced in this game.