Gokusai Kaibi (獄彩海美) is a character introduced in To Aru Majutsu no Index, and featured in the sidestory To Aru Majutsu no Index SS: Biohacker Arc. For a long time only known as the Girl in the Dress (ドレスの少女) or Measure Heart, she is a teenage girl who participates in enjo kousai or compensated dating for money. She is an operative of SCHOOL, acquainted with the ways of the Dark Side of Academy City, and the second of the three Gokusai sisters.
She has medium length blonde wavy hair styled in a ponytail and brown eyes. She usually wears a pink or red sleeveless frilled dress, leaving her shoulders bare along with necklaces and bracelets and white sandals. She often has an expressionless disposition.