Snow tires for Gunma in December end

We have a plan to visit gunma safari park and onsen areas (kusatsu onsen) Please advise whether we need snow tires car or normal tires is enough.

Best regards,

You definitely should have snow tires when visiting Kusatsu Onsen. The safari park only rarely gets any snow, and there is snow in the forecast for the rest of the year as of now.

What about the other parts of Gunma? I'm planning to visit the first half of December this year. Takasaki, Ikaho onsen, Shima onsen, Hoshii onsen.

Takasaki: snow is very rare
Ikaho onsen: it snows sometimes
Shima onsen: it snows quite often
Hoshi onsen: it is usually snow-covered

Here in Canada snow tires are recommended once temperatures consistently fall below 7 degrees Celsius. The rubber in these tires is softer and "stickier" and helps for driving on frozen bare pavement and in icy conditions too. I am guessing snow tires would be the same in Japan (especially since many of our tire brands are Japanese!)