First of all, I'd have to object to your offhanded exclusion of the Inuit, since, conversely, there are people living in tropical climes who, even in the inferno of summertime, relish the sweaty, scalding pleasures that come from a cup of coffee, a big bowl of soup, or even--paradoxical as it may seem--a hot bath. Thus, who is to say that in one's native Arctic environment, a frosty treat wouldn't be just the thing to hit the spot?
Second, I would have to reemphasize that that, no, I mean the Japanese really love ice cream. This is a country that has ice cream vending machines, sometimes with fifteen different flavors. Living near what could qualify as a tourist attraction*, I've witnessed people happily digging into ice cream cones with spoons (I'm not sure why but you always get a little plastic spoon with your ice cream cone, which most people seem to favor over the use of their tongue) at eight in the morning. And if you peruse the ice cream cooler at your nearest 7-Eleven, alongside the ubiquitous Haagen-Dazs vanilla and yuzu sorbet, you'll find the most amazing selection of "ice," which is how ice cream is fondly referred to in Japan: Muscat grape popsicles with whole grapes suspended within; seasonal offerings (peach tea in the summer, marrons in the fall, etc.); and even Fauchon ice cream with flavors like darjeeling and roasted fig.
Of course, to each her own, and Japan too does things her own way or sometimes not at all. Over here, homemade ice cream sundaes are one of those things that aren't done. You want proof? Try finding toppings of any kind in a regular Japanese supermarket. You won't. No hot fudge, no caramel, no Magic Shell Twix--can anyone tell me what this is exactly?--no sprinkles, no whipped cream in a spray can. Ice cream generally comes in single servings. You lift off the lid of the little cup, peel back the plastic flap, and dig in. What you won't see in most homes after dinner is big bowls heaped with creamy scoops of Dryer's just begging to be condimented like an overdressed tart. In fact, I don't think I've ever even seen an ice cream scoop for sale.
Another possible explanation for the unpopularity of ice cream toppings--and condiments in general, now that I think about it--is that the average Japanese consumer does not try to impose his or her preferences on established products. For example, if you don't want ketchup on your burger, then don't go to McDonald's. Do not ask the nice, young lady taking your order if you could get a burger made without ketchup. Such an illicit request could send the establishment into total meltdown, resulting in: the manager coming out front, possibly venting his fear and confusion on the nice, young girl who tried to take your order; tears shed; much frantic hand waving; and you, after many hours, exhausted and famished, escaping (a) empty handed or (b) clutching a burger with ketchup.
In Japan, if an ice cream were meant to be eaten with raspberry syrup, then there would be a little individual-serving pack of raspberry syrup neatly affixed to your cup of ice cream. Otherwise, “just eat the bloody ice cream, it's good as is” would be the general sentiment.
Now this is not to say that there aren't sundaes in Japan. I daresay you could find them on the menu of just about any family restaurant in the country. I just don't like most ice cream toppings, with whipped cream, sprinkles, and maraschino cherries topping (sorry) my loathing list. I'm not too fond of the Japanese versions either that employ layers of corn flakes or cubes of jello.
Which brings me to the whole point of this post. Last night, I came up with a really good pseudo homemade topping: melt five or six chocolate-covered coffee beans (I dipped into my small stash of Bernard Callebaut, which uses bittersweet chocolate and coats each little ball in a dusting of cocoa powder) in a few teaspoons of milk, add the tiniest pinch of salt, toss in some chopped roasted almonds to coat, and carefully spoon the creamy mixture over your single-serving cup of ice cream. The idea isn't revolutionary, but the coffee beans add a wonderful crackly crunch and aromatic little bursts to each bite.
*The local tourist attraction to which I refer is a park with trees in it, because in Tokyo, a "park" could just as easily be a five-by-five-foot plot of dirt. We actually get tour buses at our park.