Shikō

The Shikō (四光, lit. Four Lights) are four individuals who all are very powerful and respected. The title has said to be being passed down to generations after the current four, however, this is not known.

Overview
The Shikō each are prodigies in one of the four Shinigami Combat Skills - Kidō, Hakuda, Zanjutsu and Hohō. Each one is an almost unrivaled specialist in this area.

Formation
The Shikō were formed after all four defected from the Soul Society - due to their great skills, they began being known as the Shikō. How this occurred is unknown, however, it is most likely a coined title to categorise them.