"Army of One" is a bonus story after the conclusion of Hellstar Remina. One of the most popular Junji Ito's one shot story, "Army of One" is unanimously praised by readers and is often said to be Ito's magnum opus - even as far as saying the short manga is better than it's parent manga, Hellstar Remina.
Michio is a hikikomori (a person who remains shut inside the house and withdraws from society.) One day, his former classmate Natsuko Horie invites him to attend a class reunion for their "coming of age" ceremony - everyone from their class in middle school turns 20 this year and will legally become an adult in Japan. Meanwhile, the dead bodies of a couple who went missing are found sewn together with fishing wire.
Michio reluctantly agrees to go to a cafe with Natsuko and two former classmates, Noriyuki Sakai and Keisuke Kasagi. However, upon learning that Natsuko is about to marry Sakai, Michio becomes dispirited and leaves. On the way home he discovers six dead bodies sewn together. A plane flies overhead and drops fliers for the "Army of One", which regularly advertises on the radio for new members; but does not provide any details.
Michio learns of internet rumors that the Army of One is behind the so-called "stitch murders." Keisuke disappears after attending a singles mixer (which Michio declined an invitation to) and his body is found several days later, sewn together with those of the other party guests. On Christmas Eve, the "Army of One" song plays over the radio and the following day, hundreds of dead bodies turn up, sewn together into bizarre patterns and decorating the streets and Christmas trees.
The Army of One is officially labeled a terrorist organisation, though no one is sure who or what the Army really is; with some speculating they are an alien presence. The class reunion and "coming of age" ceremony go ahead in spite of official warnings not to congregate in groups. Michio is caught trying to sneak in to the ceremony to see if Natsuko is safe; she persuades security to let him in, but when they arrive, all five hundred people who had been waiting for the ceremony are missing. They later turn up sewn together, including Natsuko's fiance Sakai.
From then on, people avoid all forms of social contact or leaving the house. Michio calls Natsuko, who is depressed over Sakai's death and becoming suicidal. Michio is prepared to risk his life and go to her house to keep her company. As he heads to see her, the Army of One planes fly overhead and drop fliers; but the Japanese air force arrives to do aerial battle with them. Michio, heartened by the prospect of the Army of One's defeat, runs over to Natsuko's house to tell her he loves her. He finds her sewing her (dead) parents and their dog together, singing the Army of One song to herself. Overhead, the military planes have somehow begun dropping the Army of One's fliers as well.
- The planes dropping the fliers could be a reference to the allies dropping propaganda material during WWII to citizens living in areas sustaining bombings although in "Army of One" the effect of the fliers is way more amplified and dangerous. The military planes (Fighter Jets) sending the fliers out at the end of the story could be a nod to this.
- The "Serial Killer" carrying out the murders was never caught and the ending suggests that it is not the work of a single individual but a form of mass hysteria caused by the brain-washing fliers being sent out in great effect.