Sitting King

Sitting King (居玉 I-gyoku) is a formation where a player keeps the king on its original square, without making a castle.

It is used in many rapid openings, where there is not enough time to make defenses or when the center is safer than the side. E.g. Not putting king in Yagura against a Yagura Destroyer formation.

An old proverb goes "Sitting King is like a duck" (easy to be hunted). In modern times this view has changed and in professional games we see more of this type of shogi, especially in Bishop Exchange Opening.