Shikai is the initial form of a Zanpakutō, a weapon used by Soul Reapers in the anime and manga series Bleach. Each Soul Reaper's Zanpakutō has a unique Shikai, which is activated by calling out its name. This form grants the wielder special abilities that can be used in combat. To unlock Shikai, a Soul Reaper must establish a bond with their Zanpakutō, often through training and understanding its spirit. This transformation allows for enhanced power and new techniques, making it a crucial aspect of a Soul Reaper's abilities in battles against Hollows and other foes.