>>543689421
>>543689678
She's 3 meters tall in the anime because she's a Flatwoods monster and that's how big they're supposed to be. The manga took a lot of liberties, but making her human sized is a pretty boring change, honestly. The size is pretty much the only known thing about Flatwoods monsters.

And, yeah, she's obviously canon. Even if you've only played DL and didn't watch the manga, you'd have noticed that she's involved in the plot of the events and is Zwijo's henchwoman.