Ninja Mouse
From MHWiki
"Known for its extreme rarity, speed and intelligence the ninja mouse is one of the most challenging mice to catch. A hunter will learn much from catching such a cunning foe and is therefore worth a bundle of points."
The Ninja Mouse is a breed of mice found in various locations. They are worth at least 350 Gold and considered moderate to catch.
For a hunter to advance past the Mountain stage and reach the Laboratory, the hunter must be a Master and catch a Ninja mouse in the Mountain that drops Burroughs Laboratory Map Pieces. Not all Ninja mice will drop the necessary map piece to advance to the Laboratory.