|Class and Year||1-F|
|Physical and Vital Statistics|
|Manga||Volume 2 Chapter 7|
Ruri Ninjabayashi (忍者林 瑠璃, Ninjabayashi Ruri) is an android created by the Mahogasawa Foundation who serves the as the shinobi in Souta Hatate's party, and is introduced in the story as a secret weapon to help the Quest Dorm in the school's athletic tournament games. She frequently asks yes–no questions on operations she is about to perform, and is programmed to act like a little sister to Souta.
Because Ruri is a robot she doesn't show a lot of expressions on her face, but she always want to helps everyone from the dormitory. She has a reserved personality as Mimori Seiteikouji said.
Ruri was created by Mahougasawa electronics, she is an android imouto, newly developed to take the imouto position in a family.
She helps Souta Hatate with the flags and removing his death flag.
- The name Ruri means "lapis lazuli" (瑠璃).
- Ruri's surname Ninjabayashi means "ninja" (忍者) (ninja) and "forest" (林) (hayashi/bayashi).