The End of Summer and Your Sound Natsuki announces to the school and his friends that he plans to return to the mainland to finish his education at the Academy. However, instead of studying to be an astronaut like he originally wanted, he will focus his studies on Humanoids to learn better ways to build relationships between them and humans. Atri has also decided to accompany Natsuki to the mainland as well. Everybody supports their decision and plan for a big farewell party. However, that night, Atri suddenly malfunctions and shuts down...