It can probably grow big at will and has size shifting powers like most of the newer depictions of yukkuris >_> (I am kidding. Takumi just probably made a mistake with his proportions again or these Youmus are the smaller yu variety)
Hilariously enough, the most commonly depicted violent yukkuri is the one that does not have its tohou character equivalent's ability. Hell, flans are not even shown to have regeneration while Remilias have that ability.
When was the last time I mentioned a Tankbusting Flan? This one should be large enough to carry the payload of 2 Warthogs.
Assuming the youmu is 2 feet tall, This flan will be about 6 to 7 feet tall only -_-. I have no idea if there are other stories other than the english story of a bodied flan keeping a human enslaved depicting a flan as having super strength.
So Takumi's predator can actually be a threat to humans as well. Neat.
Any heavy enough yukkuri can be a threat to humans if they drop down from a high enough elevation to let gravity do the work and hit vital unprotected areas of the body.