Ninja in history

From a review (with the great title "Silent but Deadly") of a new book about ninja:

But what did anyone actually know of ninja? They were mostly men, sometimes masked, hiding in shadows, able to move undetected and to use a host of martial skills to achieve their impossible missions. Unlike the death-obsessed samurai, they were pragmatic. They were often sent to spy out an enemy stronghold and to do this effectively they needed to return successfully to base. Assassins of infinite patience, they were light (the ideal ninja was a flyweight 132 lb), flexible and able to hide by hooking on to ceilings. They could silence dogs, and disguised their body odour with a bland tofu diet. One famous ninja was a dwarf who, according to some accounts, assassinated a heavily guarded warlord, Uesugi Kenshin (who may actually have been a woman in drag), by hiding in his castle toilet and drilling him per anum with a telescopic spear. Man reasonably speculates on this story and wonders how a shit-coated dwarf ninja managed to sneak out of a castle on high alert.