What: The seemingly infinite flavored varieties of Nestlé’s Kit Kat bar available solely in Japan. The ones here (yanked from the best gallery on the internet, Fried Toast’s “Kit Kats of the World”) are, left to right: fruit parfait, Universal Studios brown and white, mango, green tea, apple, I-stick (to be eaten frozen), Nasu-Kogen milk, petit strawberry, doubleberry, bitter chocolate, Bretagne milk, pumpkin, apricot seed, azuki red bean, strawberry milk, wa guri chestnut, anko and matcha tea, “gold” (with fudge and cocoa powder), winter strawberry, sakura cherry blossom, white peach, choco-banana (two views), and yubari melon (similar to cantaloupe). Yum.

Why: The Kit Kat is a British invention, first released under the name Rowntree’s Chocolate Crisp in 1935. As it passed to Nestlé and later Hershey, the name Kit Kat described only a layered chocolate and wafer combination for six decades. Then Nestlé’s UK division tried a trio of experiments in the mid-1990s: orange, dark chocolate, and mint. Their limited success was all the encouragement that Nestlé Japan needed. Starting in the late 1990s, their scientists knocked out many dozens of flavors. Some are available only in specific provinces; edamame flavor can only be found in Yamagata prefecture, while dainagon azuki bean variety can only be found in Hokkaido prefecture. There is nothing they won’t try, which means they will never run out of new products. (For another view of the history, take a trip through Nestlé Japan’s Kit Kat Museum. It’ll help if you know Japanese, of course.)

Impact: Kit Kats have succeeded becoming the rarest of things, foreign-brand products with a uniquely Japanese appeal. This was aided by a lucky coincidence: the name resembles “kitto katsu,” a phrase which Japanese schoolkids use to wish each other luck in class. And so Kit Kats dominate the country which is most dominated by junk food. There is a gentleman’s agreement that they can’t be exported, even throughout Japan. This merely adds to the allure, of course; people who’ve already tasted dozens of these will travel to Japan to try Hokkaido blueberry flavor or Kobe pudding flavor. For many fans, it’s edible Pokémon: gotta eat ’em all.

Personal Connection: Evon and I are irredeemably addicted to Japanese junk food: Pocky, Pretz, Hello Panda, the like. On her return from a Japan trip, Evon’s flight attendant sister Lynn brought us the salted watermelon, banana, azuki red bean, and green tea Kit Kats. Then Evon traded some craft materials for another box of lemon vinegar, custard pudding, baked potato, grilled corn, winter strawberry, apple vinegar, sakura cherry blossom, and sesame-glazed potato Kit Kats. And we’ve just scratched the surface. If you go to Japan, you have a standing request to further our education.

Other Contenders: two very different German reinventions of the hazelnut, the Ritter Sport Voll-Nuss and the Toffifee; the richer UK version of the Cadbury Dairy Milk Fruit & Nut Bar; the best of our best, the Ghirardelli Dark Raspberry; Australia’s coconutty Cherry Ripe Bar, surely the only candy bar named after a 17th century English folk song.