Always seen wearing a gas mask, he's a man who stands out in the crowd with both his unusual demeanor and his attire. He drops in and out of Aoba's life, and for reasons completely unknown, insists on calling him "Master".

Appearing at Aoba's home uninvited, he joins the rest of the group outside to investigate the sudden chaos. Without warning, a blinding white light streaks across the sky, bringing a chain of entirely inexplicable events along with it...