There are a lot of Japan-themed snack boxes, and for good reason. Japan has some of the quirkiest snacks out there. (Tomato-flavored chocolates, anyone?) I like TokyoTreat the most, as it covers the whole spectrum, offering sweet, spicy, and salty treats. The snacks are generous in size too. I was able to share the contents of my TokyoTreat box with five other people. But it's pricey, running you $38 per month if you don't subscribe annually. It also has longer shipping times than some of the other boxes on this list.
Each box comes with dagashi (which is similar to penny candy), a DIY candy kit, and several other snacks. Mine had a bag of sakura-flavored Kit-Kats, which were my favorite, but really, every snack inside was awesome. You can also “activate” your box by confirming delivery each month, which will earn things like discounts and giveaway entries.