I traveled Hokkaido/Osaka/Kyushu so far. The latter two is with kids.

If u go with kids i highly recommend Kyushu. Can rent a car travel everywhere u want. A lot easier to travel around. Public transport in Japan especially with kids not so easy, and expensive if u have more than 1 kid.

i rented toyota Noah. 7 days cost about 130000yen total.

Need international license. Very important. Do not forget to bring, Japanese culture very rigid they wont give u the car if u cannot show the original copy.

Driving there easy level la compared to Malaysian traffic. The road sign very clear, it's like the Japanese very ultra worried u get lost. They even draw the road nicely so u know which lane to follow so u wouldnt have the sudden need to change lane. Malaysia punya traffic really love to encourage ppl to jump lane, last minute turn/exit. The road layout there super well planned and the person who planned it actually drive in the town. Really different than Malaysia where the person who design it macam tak pernah drive on that road ever. Japanese driver also very chill most of the time, always maintain safe distance even if u drive well below speed limit. In Malaysia u drive how fast also u still got ppl cucuk ur backside pressure u to go even faster or they overtake u show their lanciao face beside u before speeding away.

All in all driving in Japan damn easy. The only hard part is parking but only in the city. if u travel outskirt this is non issue. Petrol pump same like Malaysia self service.

Airbnb or hotel more or less the same. I book hotel cos traveling kids i do not want to have another potential headache dealing with house owner and all. And i LOVE staying in hotspring area.