The service is simple, no fancy tech (it's just a bunch of Python). Possibly the initial appeal was that random-boxes-of-surprises services were rare, and my openness with the numbers.
Kudos to you, Bemmu, this is a very fun idea, and I hope you continue to see success from it.
Let subscribers pick their preferred categories and allow them to choose the amount of money they want to pay each month + shipping costs,
then you go out and buy random things from one or more of those categories (in order of user preference), and keep a record of which items you sent to each customer, to avoid duplicates.
Social fluff: Let users post on-site reviews of the items they receive from you.
Ideal outcome: People discover the uniqueness of Japan, share it with their friends and other users, and you help spread some joy and pocket the change.
But then he'd be competing with established players like http://shop.j-subculture.com/
Personally, what I don't like are the kits where you have to mix things with little cups of water and such. They're never satisfying, and I think they include too many of them.