Janken: rock-paper-scissors in Japan

Rock, paper, scissors, janken, and a handful of other names. Who hasn't settled a small argument with this game? It shows up in films, series, anime and cartoons, and the rules are so familiar that nobody pauses to explain them.

In Japan the name is janken (じゃんけん). The count that sends both hands out together is jan-ken-pon (じゃんけんぽん), and jokenpo is the Portuguese form of that call. The questions that usually stay unasked are the useful ones. Where did the three hands come from? What were people throwing before stone, paper and scissors?

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The three hands

Most games are between two people. The players face each other, share a count, and show a hand at the same moment. On jan-ken-pon, that moment is pon. Each shape has a short Japanese name beside the one in the drawing.

• Rock, guu (グー), is a closed fist. It beats scissors and loses to paper.
• Paper, paa (パー), is an open hand. It beats rock and loses to scissors.
• Scissors, choki (チョキ), is a fist with the index and middle fingers extended in a V. It beats paper and loses to rock.

A win for one player is a loss for the other, so the round is a zero-sum game. When the hands match, the round is a tie. In Japan a tie is aiko (あいこ), and the players throw again until one hand wins.

Where the hands came from

The earliest written mention sits in Wuzazu, by the Ming-dynasty writer Xie Zhaozhe, around 1600. He called the game shoushiling and wrote that it went back to the Han dynasty, from 206 BC to 220 AD. Xie was writing more than a thousand years after the Han. The book records the tradition as he knew it in the Ming period.

Hand games in this family later reached Japan. The ones built on three signs are called sansukumi-ken (三すくみ拳). Ken means fist, and sansukumi is the deadlock in which each of the three fears one of the others. The oldest of these in Japan is mushi-ken (虫拳), brought over from China. Its figures are a frog, a slug and a snake. The frog, shown with the thumb, beats the slug, shown with the little finger. The slug beats the snake, shown with the index finger, and the snake beats the frog. The Chinese game used a centipede in the slug's place. The characters for that centipede were read as the characters for a slug.

Jan-ken is the sansukumi-ken that uses stone, paper and scissors. That form settled in Japan in the late nineteenth century, and the modern game comes straight from it. By the early twentieth century it had traveled with Japan's contact with the West. English took the names of the three Japanese hands. In much of the rest of East Asia the open palm means cloth.

When a plan actually helps

A player who really picks a hand at random leaves no advantage, because each shape wins against one of the other two. Most people leave a trace instead. They repeat a hand, copy the other player, or avoid the shape they just lost with. The three shapes stay balanced. The person choosing them is the part you can read.

No Game No Life puts that on screen in the episode "Challenger". Sora tells Stephanie Dola he will only throw paper. She works through the chances, decides he has no reason to pick anything else, and throws scissors. He throws rock and wins. The line about paper was the trap.

Holding a hand back until the other one is visible is a separate problem. In ordinary janken, delaying on purpose so you can answer the hand you just saw is called ato-dashi (後出し). That late throw is a foul, and it counts as a loss. A party game called ato-dashi janken asks the second player to answer after the first hand is already showing. Ordinary janken still wants both hands out together, on pon.

More than three hands

A larger set stays fair when the count of hands is odd, and each hand beats exactly half of the others while losing to the other half. Three does this with one win and one loss. Five does it with two wins and two losses. Extra hands cut the chance of a tie when people really spread their choices, and they add pairs you have to remember.

One popular five-hand version is rock-paper-scissors-lizard-Spock. Spock uses the Vulcan salute from Star Trek. Lizard is the hand pinched into a mouth, the way you hold a sock puppet. Spock crushes scissors and vaporizes rock. Lizard poisons Spock, and paper disproves Spock. Lizard also eats paper. Rock crushes lizard, and scissors decapitates lizard.

The first time I saw it

I remember the first time I saw this game in Dragon Ball. I still think of it as one of the shows that settles the most arguments with these three hands. The round I go back to is the one in No Game No Life. Other series settle a scene with the same three hands, and some of them are built around games from the start. Do you remember another one? I can think of several.