Robot Imouto: Aratame Jinrui Kai Kyoudai

is a Japanese light novel series written by Kei Sato, with illustrations by Aoi Saga. The series began publication on August 10, 2004 by ASCII Media Works under their Dengeki Bunko publishing imprint.

Synopsis
Iwatetsu Iwao is a slightly old-fashioned Bunkara high school student. However, from the moment he was appointed as the pilot of Moemi-chan, the final humanoid decisive weapon, his younger sister robot, his life, which has been a mediocre man, will change completely! C. Scotty, an invader from outer space who stands in front of Moemi-chan No. 1! Only "Moemi-chan" can save the earth from their witchcraft! go! Iwao! It's time to release the true "Sister Power" !!