Schwi bears many similarities with Shiro, but with several differences, the most prominent being two tails that come out from her back, and other machine-like features that protrude from around her body.
She has very pale skin, long, messy black hair (dark violet/maroon in the movie) and red eyes (yellow with blood red curves and black pupil in the movie). She is very slim and quite short. As an Ex-machina, it is normal for her to not be wearing any clothes.
During her time with humans other than Riku, she wore a robe to cover the mechanical parts on her body, including the piece on her head. However, the tail was uncoverable (as it was her power source), therefore Riku decided to go calling it "equipment". While she does resemble Shiro, it is likely that Tet construed both Riku and Schwi's appearance to resemble Sora and Shiro in an attempt to show connections between the two groups. This is pointed out by Izuna who believed Tet was lying about certain parts of the story. Tet confirmed some portions of the story were false only moments later.
Before she made proper contact with humans, Schwi's behavior was similar to that of a stereotypical artificial intelligence. She could absorb and process data and intelligence very quickly and act in the appropriate manner - a unique characteristic of her race.
However, she seemed to have difficulty in comprehending emotions and desires, otherwise characterized by her as the [heart]. Over time spent with Riku, she seemed to have started to develop her own [heart]. Her expressions and feelings became more vivid over time.
After setting her personality to mimic that of a "shy Imanity survivor", and spending a year around Riku's colony, she was unable to reset her personality back to the default monotonous mannerisms of the Ex-machina, stating that she was "stuck" in that mode.
Like other Ex-machina, she is able to assess a situation and react accordingly at blazing speeds. An example is when playing chess with Riku, she was able to record any new moves, assess the situation, and proceed correspondingly when presented with the same position in the future.
Although she took on the appearance of a young Imanity girl, she is incredibly strong to the point of nonchalantly cutting apart a boulder, ripping out a few iron plates, and lift a large metal door ten times her height over her head (to Riku's horror) and destroyed an Elven library. She is also incredibly fast as seen when she was able to travel with Riku on her back from the colony to the destroyed Elf city in half a day when traveling by horseback would have taken five days (without the use of magic, in which case it would have taken several minutes according to her).
Of the Ex Machina, she is one of the Prüfer, so she is particularly good at analysis. Despite this analysis of the [heart] took much time.
She does not require sleep nor any need to eat as she utilizes two live cables to connect to the Elemental Gallery for her power source.
The Ex-machina are a hive mind unit, however Schwi was exiled from the unit due to various system and logic errors. Therefore, Schwi was unable to access any of the 27451 artificial weapons stored in the Ex-machinas' linked arsenal until shortly before her death.
As she was robot and not a human, she was not very good at reading other's minds.
During The Great War, she and 3495 other Ex Machina were involved in a battle against Aranleif the Ultimate and his seven followers, resulting in Riku's village being destroyed. Upon spotting Riku, she was puzzled by his reaction and decided that further analysis was required. However, her study generated an abundance of errors, which led to her disconnection from her cluster.
Meeting with Riku
Riku is searching through the Elves' ruin, and he sensed something. By the time he noticed danger, he is pinned down by an Ex-Machina. Realizing his doom upon violence, he surrendered himself. However, the female-like Ex-Machina surprised him with a kiss. After regaining himself, he questioned the Ex-Machina what is it up to, and the Ex-Machina answered that it is t learn the [Heart]. The two then leave the place.
After evacuating everyone from the hideout. The remaining reformed under Riku and sworn upon the Six Pledges. They then each went out in their direction, moving behind the current of war. Schwi remained with Riku to plant 32 Einwiek so that they can manipulate an attack to gain the Star Relic.
After they planted the 23rd and Riku's meeting with Shinku Nilvalen, Riku's body succumbed to the damage. He is treated by Schwi, but still, lose his left arm and eyes, as well as his right arm damaged. He then rested for a day, and have Schwi hold his hand in his rest.
Despite Riku's request, Schwi had gone out alone to execute their project. She successfully planted the 24th, but was caugt in a skirmish with Jibril, who sought to collect her head as a trophy, as the Ex-Machina have become one of the [Rare 5]. Jibril was unable to get her head in the end as she used Heavenly Smite on Schwi, and she was completely obliterated. However, she was able to provide the data that Einzieg requires to inform Riku and protect the ring she got from Riku using magic (Kein Eintrag). She finally understood the meaning of love in her last moments before death.
- When Riku asks for the Ex-machina's name, she replies 'Üc207Pr4f57t9', to which Riku immediately responds by asking her for a more human name. Her first choice is Schwarzer (シュヴァルツァー) meaning 'Black One' in German, which interestingly contrasts with Shiro's name meaning white in Japanese. Eventually, they both settle with the name 'Schwi'.