inadvertently triggered a hazard due to leaking of a developing nanomachine. The city and the surrounding area that the lab is located in is ultimately demolished but the scientists had actually evacuated to safety from the lab before the place was destroyed. Kou wishes to uncover the truth about what happened that day and to prevent another tragedy from occurring again, as his girlfriend Sora was killed by the nanomachines. Characters The protagonist of the story. A free mercenary and an excellent simulacrum pilot. Kou has been chasing after the truth behind the incident known as "Gray Christmas", in which he lost the person most precious to him. As he recovers his memories and experience new ones, he reaches closer to the truth. A mercenary and Kou's subordinate. Referring to Kou as Lieutenant, she becomes the one to guide the amnesiac Kou. Like a commander, she scolds and encourages Kou whenever he is in the midst of confusion at times. Even though she is polite and gentle, her gestures and expression often give people a cold impression. Rarely letting out her emotions, she often remains composed. She is merciless towards enemies. Her actions usually put Kou's safety as top priority, so much that she may even give up her own life for Kou. Kou's friend that lived with him in the Kisaragi dormitory. She disappeared after Gray Christmas, but later reappeared before then undergoing memory restoration process Kou, dressed in an army uniform and heavily cyborgized. Kou's childhood friend, a year younger. She lost her parents due to a bomb. Now she's a keeper of an internet cafe. Kou's second cousin who he considers as his sister. She's a "wizard" - a genius programmer in the virtual world. Kou's simulcrum is her gift when he was moving to Kisaragi dormitory. She works in the corporation of Kou's aunt, Ark Industry. Sora's little sister, she met Kou who saved her from bullying by her peers due to her illness. Later moved to Kisaragi dormitory. Makoto's older sister, whom she heavily adores. She died in the accident, called "Gray Christmas". Kou's best friend, who loves women and mecha. Moved with Kou in Kisaragi dormitory when they lost their previous place due to a certain incident with their upperclassmen. A woman with a childlike appearance, and a capable underground doctor, who lives in the Suzushiro City's slums. Officially runs a sex-toy shop. Leader