In the mid-80's, FN was working on a new theory in weaponry, the Personal Defense Weapon or PDW. The concept had been pioneered by the H&K MP5K, and but with body armor able to withstand 9mm rounds, FN developed an entirely new bullet, basically a cut-down 5.56mm, coupled with a bold new design.
Today, the P90 is becoming the new PDW of choice for the US Secert Service, SWAT units, SPECOPS units, and close protection contractors. The gun as become a favorite on the new Battlestar Galactica and Stargate.
The FiveseveN is the embodiment of Mr. Shirow M5 5mm pistol weapon concepts in Appleseed and Ghost in the Shell. Shirow's little workhorse pistol could be used like a PDW, defeating hostiles in close-quarters. The same could be said of the FiveseveN, its 20-round magazine and specially developed bullets allow it to be a PDW.