Shakti

"Shakti" (シャクティー) is an infant which is part of a certain Hindu sect in India. After her nursing mother Harisha took her to Academy City, she is left in the hands of Index (and by extension, Kamijou Touma), who later find themselves involved in the issue of the child's fate.

Etymology
is a Hindu concept; a primordial universal energy embodying creative power and personified in feminine form.

Background
Shakti was part of an Indian sect which considered her their priestess. At some point, Shakti fell ill due to a curse. The sect planned to use Harisha's child as a substitute for the curse to save their priestess. Harisha agreed to it at first but later regretted it. Using her position, she abducted Shakti, intending to sacrifice her to save her own child, and fled to Academy City, intending to acquire the information she required for the ritual from Index's mind.