So with the neverending hunger, as well as being able to murder the tiger when half the size... I'd say she's a weasel or shrew. Probably weasel. They'll starve to death if they go more than a few hours without eating, and eat a huge percent of their body weight every day.
Scientists say that if weasels were 60 pounds, they would kill all life on the planet in less than 20 years. They're savage, powerful (for their size), and incredibly fast.
Shrews are actually even scarier. They're faster, and are actually venomous. They also require even more food a day. Other than that, they have all the same characteristics as a weasel if you scaled them up.
@MoonHermit
I doubt she's a wolverine. Its possible, I guess. But the series seems to like their lesser known savages in their most dangerous characters. Though a wolverine may be able to kill a tiger. They're pretty savage, and have been known to kill even large bears.
I'm also beginning to worry about Inui. Its getting a little too crowded in her head...