Snow tires required for driving to Mt.Aso?

I'm planning to rent a car and drive from Kumamoto to Mt.Aso and Takachiho Gorge during December 28 and 29. I'm not sure if I need to get a car with snow tires? Some says there's not much snow anyway, while some says it is needed.

So can somebody who really know what I should do, please advise.

The rental company is probably the best to talk to.

But even if you get an answer from elsewhere, the rental company will put on whatever tyres they deem fit for use one the day of collection.

Since you'll be renting a car only for 2 days, additional cost for snow tires isn't much. Why not be safe than sorry. It's true that it doesn't snow much. Most people live there don't even own snow tires. But as you go higher, it can get cold enough that road could be slippery. Who knows, there could be rare strong snow on the day you'll be driving. But if you want to save money, tire chains are enough for most winter days around there.

Actually, I will rent the car from December 27th to January 2nd. But the other day, I know that I might not face the snow, but those 2 days at Mt.Aso and Takachiho. That's why I need you guys recommendation. :)

I've been around there during winter a few years ago. If you ask me yes or no, I would say no, snow tires aren't absolutely necessary. But I'd add tire chains, which only costs one small additional fee, they don't charge by per day. Even when it snows, it won't be a lot like northern Japan. There will be plenty of traffic on the roads you'll be driving, most snow on road would melt rather quickly. Unless you know you're going to be driving there at night, the chances of icy roads are small during the day. However, if weather is bad and there's enough snow/ice that makes driving unsafe with normal tires, they will impose "Tire Chains Required for All Vehicles Restriction". Of course if you have snow tires, you don't need to have chains.

Btw, I too have upcoming trip to Japan. I'll be doing 17-day very long road trip. I'll drive from Tokyo to Aomori, from Aomori all the way to Sagasaki, and then back to Tokyo. I'll be driving through plenty of heavily snow areas, so I made a rental car reservation for 4WD SUV with snow tires (really expensive).

Have a safe trip!! You'll love it there ;-)