Best time to go in Spring, Kanto's summer is melting and Sapparo's winter is hell for non-natives
Also Sapparo in Spring is beautiful, so makes sure to go there first.
I think you better off visit smaller stores in town rather than restaurants in Sapparo are fking expensive, most likely because they expect travellers as their main customers, not natives.
Don't visit curated food sites, they gonna grind your pockets hard.
I am definitely not a travell agency shills, also use SHITBOX for 15% off
Also don't go to Okinawa, it is just the generic domestic tropical beach for Japanese, everything is quite expensive and qualities in not that good. Go to Bali instead.