Sources of Randomness* in Japan

As a computer scientist living in Tokyo, I've been pondering creative ways to generate random numbers. Here are four sources of randomness in Japan:

1. Good old coin flip. I know, hardly unique to Japan, but the 五円 (5 yen) are lucky.

 But if it were truly lucky, it wouldn't be a fair coin flip.

But if it were truly lucky, it wouldn't be a fair coin flip.

2. Gatcha-pon. 

Japan's take on the vending machine, often found at arcades and near tourist destinations. Prices range between 200 and 500円. Usually there are 5-7 variants in the machine, each enclosed in a capsule. Assuming an equal distribution of each toy in the machine, you can generate a number between 1 and N. This one appears to contain some sort of feline torture device:

 Don't let the picture fool you. Cats hate this.

Don't let the picture fool you. Cats hate this.

3. Blind Boxes

Similar to the Gatcha capsules, but for retail. You can find these at places like LOFT. I really like this strange girl that hangs out on the side of a drinking glass -- カップのフチ子 or Fuchiko on the cup. 

IMG_20180312_125445.jpg
 Seven choices available in this box.

Seven choices available in this box.

 I got the best one on the first try.

I got the best one on the first try.

4. おみくじ Fortune Shaker found at Shrines and Temples. At places such as Sensō-ji in Asakusa, Tokyo, you can pay 100円 to get your fortune. Many fortunes are drawn via a hexagonal shaker with thin sticks. On each stick is a number, corresponding to a drawer of fortunes (a look up table!). Often there are 30-100 in total. Randomness might be hampered by missing sticks. Be respectful of religious sites at all times :)

 Omikuji at Sensō-ji

Omikuji at Sensō-ji

What are some other ways of generating a random number from your corner of the world?

* Yeah I'm not guaranteeing a perfect distribution on the gatcha-pon, so don't use it to generate cryptographic keys, alright?