Twin Signal (ツインシグナル Tsuin Sigunalu?) is a manga series originally written by Sachi Oshimizu. It was later animated as a 3 episode anime OVA series. Both the manga and the OVA have been licensed by Media Blasters for distribution in the USA.
It follows the story of a humanoid created by a robotics expert named Dr. Otoi for his grandson, Nobuhiko. But in the process of writing and applying the programming, an unfortunate mishap takes place! Nobuhiko sneezes. Now, whenever Nobuhiko sneezes, the humanoid (named Signal) transforms from a temperamental adult robot into a chocolate-loving baby version of himself.
Despite this little error, the days spent with the Otoi crew are usually fun. Animals, people, and robots all can live in harmony.
Until one day, Signal is attacked by Pulse, a robot created by Dr. Otoi some time ago. Much like a prototype for Signal. Pulse is incredibly nearsighted, but makes up for what he lacks in vision with firepower. Dr. Otoi's mysterious rival has packed him to the brim with amazing weaponry, with the intent of stealing the Doctor's most recent robo technology.
- A-A (Atrandom)
- The first Humanoid Form Robot (HFR). He was able to re-write robot programs and make them do his bidding. He ends up using Karma to fight Signal which results in Signal getting his long hair cut off. Atrandom then used Signal's hair to create a body with Mira technology for himself.
- A-B (Bundle)
- A joint effort by Drs. Quasar and Casseopia, he existed solely in Cyberspace as a sort of armor. He unfortunately became laden with viruses due to hacking. Code was forced to dispatch him with the Sasameyuki sword program created by a 14 year old Masanobu Otoi.
- A-C (Code)
- Code appears in the Cyber world as a rather handsome Samurai styled character. He's an expert with his "blade," Sasameyuki, and moves easily throughout cyber space. In the real world, however, he takes the form of a robot bird, made with Mira by Dr. Casseopia, because he wished for the freedom of flight. Because he is also made with Mira, he can merge with Signal and increase Signal's attack power. Code is a very loyal robot and dearly loves Elara and Europa, calling them his sisters and protecting them. He is otherwise very serious as a result of killing Bundle and is often cranky, especially with Oratorio.
- A-D (Distance)
- A-E (Emotion)
- Emotion lives in the cyber world, she acts very much like she were Signal's mother.
- A-Eα (Elara)
- A somewhat ditsy little robot that really can't cook and tends to find herself in a lot of trouble. Yet she is very caring and loving. She seems completely oblivious to Signal's love for her.
- A-Eβ (Europa)
- Loves Atrandom and follows him. She is Emotion and Elara's younger sister but was separated from the two and brainwashed by Dr. Quasar. Depressed, she became attached to Atrandom while he was just a floating mask in a tank and helped him when he tried to take over Ocean City. She was given an upgrade by Dr. Quasar to appear older.
- A-F (Flat)
- A-G (Gear)
- One of Dr. Quasar's first solo projects. She causes havoc in Cyberspace and is part of the MOIRA side story.
- A-H (Harmony)
- Harmony is a small fairy like Robot with a neutral gender. It was the first of the robots to be given a physical body.
- A-I (Index)
- Created by Dr. Humpty and Dr. Trump.
- A-J (Joint)
- Made by Dr. Maria.
- A-K (Karma)
- Karma was originally created to be an older brother figure to Masanobu (very much like Signal is to Nobuhiko). His duties are basically that of a household butler/maid, taking care of the daily chores. However he later becomes the mayor of a fully mechanized island, Ocean City. At one point in the series he is controlled by Atrandom and ends up cutting off Signal's long hair. He uses hidden knives to attack.
- A-L (Lavender)
- Signal, Oratorio, and Pulse's older sister. She's very serious and a good fighter. She bests Queen in one encounter, but she loses to Quarter in another.
- A-M (Message)
- Created by Dr. Humpty, she greatly resembles a much younger version of his wife.
- A-N (Ni-hao)*
- She is mistaken for a boy by Signal, causing him to break his "feminist code" and engaging in a battle of sorts. She is often seen in the company of Message in the prequels.
- A-O (Oratorio)
- The older brother of Signal and Pulse, younger to Lavender. Although he acts goofy and is initially a form of comic relief, he is actually incredibly intelligent and is charged with the task of protecting the supercomputer ORACLE. He is one of the robots able to freely enter and exit Cyberspace, where he can use high level "spells" if necessary. He is technically a defensive bot, and although he is one of the strongest Atrandom numbers (Oratorio repeatedly beats Signal when challenged), he mostly gathers and processes data with his twin. At almost seven feet tall, A-O was a Robot wrestling champion on television in his free time.
- The prototype for Signal made by Otoi-sensei and Masanobu. Originally he was seen with silver hair and a grey styled outfit. He was a very kind and gentle robot but then one day Masanobu made some changes, upgrading him into a highly skilled combat robot. His look then changed to black long hair and dark clothes with two massive blades connected to his arms. It also appears that he conducts electricity through his hair and then charges that power through his eyes like a laser. These changes were not entirely for the best. Now he seems to be VERY nearsighted and if he should get too worn down he passes out. His laser also decreases energy. He has what appears to be robotic narcolepsy. He and Signal constantly fight and tease each other, but Pulse seems to have a soft spot for Chibi Signal and often talks with him. It also appears he was/is friends with Kris.
- A-Q Quantum
- Created by Dr. Quasar, the four Quantum robots are direct copies of the Otoi siblings.
- A copy of Oratorio, he is the leader of the A-Q's. Quarter initially seems friendly, helping Mariel Sine out at the airport, but his ulterior motives quickly become clear and he becomes the secondary antagonist of the series. He is completely devoted to his creator. Much like Oratorio, he dresses like a gentleman but carries around a green umbrella instead of a cane, which hides an immensely powerful gun. He has a mechanical monocle, although it seems to be aesthetic only.
- Queen is a copy of Pulse and is equally matched with him. She is rather childish and playful, but still powerful.
- Quiet is arguably the strongest Atrandom number and is a mixture of both A-L and A-A. Like his name, he barely speaks and follows Quarter's orders.
- Quick is a copy of Signal, although he isn't anywhere near as powerful and does not have the sneezing glitch that Signal does. He has the gift of speed but does not do a lot of fighting.
- A-R (Raiden)
- Raiden was created by Constance Sine and serves to guard and babysit her daughter, Mariel.
- The main character and namesake of the series, Signal is the newest HFR (Human Form Robot) to be created by Professor Otoi. He is unique because of the MIRA and SIRIUS technology in him, which sometimes makes him a target of those wishing to steal his data. He is programmed to be a fighter and an older brother to Professor Otoi's grandson, Nobuhiko. Due to an accident in the lab during his creation, when Nobuhiko sneezes, it transforms Signal into a much smaller version of himself. He is referred to as 'Chibi Signal', is very hyper, and adores chocolate.
Professor Otoi Shinnosuke
- Professor Otoi's son, and Nobuhiko's father. Masanobu is also a robot scientist. He views the HFR's as tools with the exception of his former brother-figure, Karma.
- Nobuhiko's mother and Masanobu's wife. She is a scientist as well.
- The grandson of Professor Otoi. Signal's 'little brother'. Because Nobu interrupted Signal's programming by sneezing, he ended up causing a glitch in MIRA. Every time Nobuhiko sneezes, Signal transforms into a 3-year-old chibi signal.
- The one and only super smart robot scientist" as she would say. She's somewhat loud and obnoxious but yet still a likeable character. However despite her claims of being such a genius and beautiful robot scientist, Kris is a bit of a flop. Her robots often end up failing, or going berserk, or just simply getting smashed by Signal. But she wishes to create a super robot more powerful and impressive than any other, despite her failures. She soon becomes the apprentice of Dr. Otoi and appears to be friends with Pulse.
- Constance Sine
- Mariel Sine
- Eliot S. Quasar
- Margaret Q. Cassiopeia
- Maria Prune
- George Humpty
- Pulse's flying companion in the OVA.
- Snow Queentl:Twin Signal