Been there twice and my last was in January 2013. It was freaking cold and we wish we didn't have to come out of the backdraft stage where fire provided sufficient heating 

I went Universal Studio Osaka on early December (when Winter started) and enjoy so much as is cooling but not sure February is freezing or same. But during the day we went, there was slight rain here and there, and it was indeed an experience where it rain icy water suddenly while myself and my son still on the ride in the air. 

If you really planned to go during winter, do be the earliest customer and make full use of the park operating hours, as they closed early. We were so reluctant to leave the place, hence after the park closed, we had our dinner at the Hard Rock (across the entrance) and after that return to the park gate and snap few more pics (in the dark). 

Most of the movie theme ride are indoor if not mistaken. Not sure bout Harry Potter now, my time (2 yrs bk) was Spiderman.. is indoor. If I recall correctly, among so many rides that we took.. only Jaws and Jurassic park is outdoor.

And for sure, when gets indoor.. it is very hot. So you gotta prepare having your jacket on and off frequently.
Not sure how far off the temperature between February from December. I went in December, we enjoy the breeze with my son happily running around without sweat. If you are worry, invest in a set of good thermal wear, along with other winter clothing necessity, that should be good enough.

I'll be going again this December, but this round won't bring my son. So not going to Universal Studio.

Haha..I forgot bout ears.. coz I was having thick long hair.. quite wind-proof and diy a fleece neck-warmer that can be pull up as head-band then cover ears, ya hubby and son have both their beanie + jacket hoodie. But ear-muff really useless.    And the glove we having not good enough. But I reluctant to take out my ski-glove 

Last visit I stayed Hotel Hillarys (in Denden town) and this December booking the same place again. 2 yrs ago I paid RM200plus per room with breakfast (3 pax room - 1 double + 1 single bed). But tis year I gotta pay average RM300 per night for double room, no breakfast.
Like this hotel due to winter, night time we basically lock ourselves in. They have machine with free flow of coffee, hot choc, tea, soft drinks. So at least we can hang around the lobby with drinks and play gadget. 

I not willing to pay similar hotel cost to sleep on the floor (though tatami).
But if really get a budget 1, then become shared bathroom.. no way.

Since you are going to Takayama, add in Shirakawa-go too.

you need to start queue at 3am 
To me is just big tuna fish la, if you have time can go queue up. For me, I didnt have enough time so I didnt go.

Silly me.. I forgot to include that haha.
Budget around rm400-500 (keeping it rm100 per person)
In that case are there any places with cheap accommodation that would be near to the subway?