Yuuri Senya

The ghost girl is an unnamed girl who appears in Toaru Kagaku no Railgun Gaiden: Astral Buddy. Supposedly a ghost and suffering from amnesia, she seeks Hokaze Junko's help in finding out who she was.

Appearance
The girl has long dark hair and wears a white dress.

Personality
Playful, mischievous, and excitable, she is always to meet new people. In her first act upon meeting Junko is kissing her. From then on she would cause trouble for Junko whenever she possesses her body, much to her chagrin. In spite of this, her friendly nature and tenacity eventually won Junko over, and she agrees to help her investigate what had happened to her.

Background
The ghost girl's background is unknown, as she doesn't have any memory of who she is, though she suspects that she is likely the ghost of someone who has died, given her ghostly characteristics and circumstances.

Astral Buddy Arc
After resolving an incident involving a series of pranks previously believed to be the work of a ghost but actually the work of a girl infatuated with Hokaze Junko, Junko talked to the doll involved in the incident, only for the genuine ghost girl emerge from it and greet her, scaring her into unconsciousness. Afterwards, the ghost possessed Junko's body and took her back to her room. In her subsequently dream, Junko tried fleeing from her only to wake up in her bed. The ghost then appeared in front of Junko, scaring her after which she pointed out to Junko that she was naked much to her dismay. She explained how she brought Junko to her bed and also pointed out that she is late for school.

Abilities
The ghost girl displays a number of traits which are commonly associated with ghosts, including, floating in midair, being visible only to certain people and the ability to living beings.