Shirai Kuroko is a Level 4 esper and a student of Tokiwadai Middle School, as well as a member of Judgment. She can usually be found accompanying the third-ranked Level 5 esper Misaka Mikoto — her best friend, partner, and roommate. Though a minor character in Toaru Majutsu no Index, she gets a starring role alongside Mikoto in the Toaru Kagaku no Railgun sidestory.

The name Shirai Kuroko is quite interesting because it contains both the meanings of “white” and “black”.

The family name “Shirai“ can be literally interpreted as “white” plus “(water) well”; while the given name “Kuroko” is more interesting: as a name, it can be interpreted as the stem “Kuro-” plus the suffix “-ko” – which is commonly seen in Japanese female names (other examples include Saten Ruiko and Kongou Mitsuko); while not used as a name, the term “kuroko” means stagehands in traditional Japanese theater, who dress all in black.