Ruri Ninjabayashi

An android created by the Mahogasawa Foundation. She serves the as the "shinobi" in Souta'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.

(Source: Wikipedia)