|Spoiler Alert: This page contains details about plotlines described in the Visual Novels. Do not proceed unless you want to be spoiled. |
During Unlimited, due to Kouzuki Yuuko's failure to come up with a solution to the problem of creating the 00 Unit's body, the 00 Unit was never seen in the game. Little to no detail was given about the 00 Unit, apart from that it was connected to the brain in the jar which Yashiro Kasumi was communicating with vaguely.
During the first part of Muv-Luv Alternative, the 00 Unit's situation remains the same as in Unlimited. However, with the help of Shirogane Takeru and Yuuko from the Extra-branch world, the Yuuko in the Alternative-verse solved the problem she had with creating the 00 Unit.
During Episode 8, it is revealed that the brain Shirogane Takeru frequently saw was, in fact, the remains of his childhood friend, Kagami Sumika. Specifically, the Sumika of the Alternative world. After the 00 Unit was successfully created, it began to emulate the personality of Kagami Sumika, however since the emulation involves constantly reliving a traumatic past memory, the 00 Unit was left in a useless, unfixable state. Kouzuki Yuuko hypothesised that Shirogane Takeru maybe able to fix or tune the 00 Unit thanks to his property as a Causality Condutor. Her hypothesis was correct, and with time, the 00 Unit slowly recovers "her" mind, going from an autistic-like state, into a child-like mentality, and finally into a condition befitting a normal human. However, after making a seemingly full recovery, it was emulating emotions of deep, intense hatred unseen among anyone else of the cast.
It needs to be noted that Kagami Sumika of the Unlimited/Alternative world is not the 00 unit. Professor Kouzuki Yuuko mentions that humanity does not possess technology to allow the brain to exist outside the cylinder. This means that when Sumika's "data" was pulled to the 00 unit, the Kagami Sumika of the Unlimited/Alternative world was killed. Professor Kouzki Yuuko confirmed this by saying that she directly killed her, whereas Shirogane innocently helped.
The 00 Unit needs to be purified, so she has to be connected to a Reactor regularly. This is because the liquid that acts as the coolant for the Unit's G-Element based 'processor' degrades over time, more so when the Unit is using its abilities to the limit, and if the processor overheats it may result in Kagami Sumika's personality data being damaged or erased.
The 00 Unit has ESP abilities similar to that of Yashiro Kasumi, as it was created to communicate with and understand the BETA, achieving that which Alternative III failed at. The difference between Alternative III's ESPers and Alternative IV's 00 Unit, is that the latter was constructed in a manner in which the BETA should not recognize her as a carbon-based life form. Kouzuki Yuuko mentions this is the reason why she named it the 00 Unit: zero biological basis, zero human lifesigns. In other words, it is a completely artificial being emulating a human.
Later in the story, and despite being a machine, the 00 Unit grows too close to Takeru, and upon realizing it, decides to push him away in "guilt" and in "fear" of him getting hurt. Despite its attempts, Takeru doesn't give up on it, and as a last resort it chooses to let him see the emulated memories of Kagami Sumika when she was in captivity in the Yokohama Hive directly through telepathic projection from her memories. It showed him the images of him being eaten alive as he tried to save Kagami Sumika and the immediate resulting situation where she didn't grieve for him or attempt to avenge him and instead kept gleefully sexually fantasizing about him as the BETA experimented on her sexual organs, all in hope to make him feel disgusted enough to leave. Her heart eventually gave in from the intense orgasms, so the BETA gave her a larger heart, enlarged sexual organs and repeated the experimentation, only this time with even more intense orgasms and then repeated the cycle as necessary.
The BETA eventually cut away the human body parts that did not directly contribute to the feelings of pleasure, meaning she was left as only a brain and a spine. From that day onwards, to the point of her death, she spent every waking second experiencing nothing but intense orgasms, with Shirogane Takeru as the most likely subject of her fantasies (a major factor in allowing Extra Shirogane cross dimensions). Despite seeing all that, Takeru says he does not care in the slightest about the past and keeps pursuing her until she breaks down in tears and admits her feelings for him.
During Operation Ouka, Sumika, with the help of Kasumi, successfully lets the Superior establish a conversation with Takeru via proxy telepathic communication. The Superior is willing to communicate based on the fact it acknowledges the 00 Unit as a life form, due to its non-carbon material makeup.
The Day AfterEdit
During the after credits scene in Episode 03 of The Day After, the 00 Unit's brain was seen in Takeru's flashback after he had come across a similar brain in one of the halls of the JFK Hive. When he saw the brain, Takeru thought about how it (and in extension the 00 Unit) must have felt terribly lonely in a terrible place like the hive. He crushes it out of sympathy with his Type-00C.
- In Ayu-Mayu Gekijou Episode 2, Suzumiya Haruka was rebuilt as a 00 Unit after her accident, complete with a deadly ahoge.
"But Takeru-chan still... told me it was alright, and that he'd protect me."
"My mind and body... aren't human anymore."