Amaterasu

calm, emotionless, disciplined, loyal, knows her position, hard worker, egoistic. Though when she's around Metallikana she blushes easily, turns a little creepy and shows signs of Yandere (not going as far as to kill others but really obsessive, watches every of her movements, stalks her sometimes)

Likes: Metallikana, housworks (cleaning, cooking) – only if it's for Metallikana though, fighting, winning, being dominant over others (except: Metallikana), her blindfold (more about that later), training, taking a walk in the evening when it is quiet

Dislikes: others being close to Metallikana, too many/ too loud noises, her eyes, having to repair her mechanic limbs, water (since that ruins the mechanic limbs)

As every Bot, Amaterasu was created artificially. The material used for her body was diamond. A rather unusual choice, since there’s not really an easy way to model diamond. However as some of the already existing Bots went up in Level their once weak material grew stronger, which is how they were able to built Amaterasu’s body. So far she's the only bot consisting of diamond. Of course that's not her only material. She does have a doll like skin as well as real hair, like most other bots. Additionally she has 4 artificial limbs attached to her back. (Though those limbs are optional, she can take them off. They are really helpful in fights or for training but hindering in everyday life.) They are made of steel and can be used as swords or simply support her in combat by increasing her mobility.
Amaterasu also has control over the diamond her body consists of, so she is able to transform her arms into blades, which is the technique she uses for fighting.
If Amaterasu were to take of her Blindfold she could see everything around her, she has a 360° vision that even works very well at night. Her eyes look a little like insect eyes, as they are made entirely of diamond. There's no white part, no pupil, everything is just a crystal. While this amazing sight is a great ability, it was really tiring for her to use. She often had a headache because of it. One day in a training session she had to put on a blindfold to learn how to fight without sight, in case she couldn't rely on her eyes for whatever reason and she loved it. So she kept wearing a blindfold constantly. She only takes it off for Metallikana or in case she really needs to look at something, but after a short adjustment period she could do almost everything with the blindfold on. She even learned to enjoy Metallikana’s presence without seeing her.

As already described, Amaterasu was born a Bot, which are Robots created to fight. At first she didn't have any emotions, she didn't have a personality, she didn't have free will, she was just following orders. She started living in the bot training camp under the supervision of Metallikana. The bots, training there, were all part of her squad which is a big part of the bot army. Amaterasu was doing very well in the camp, so she leveled up fast. (Levels can either be reached after a lot of training or through an emotional development, Level 10 is max Level) When she reached level 2 she became stronger but she also developed the first part of her personality, which happened to be admiration for Metallikana. From that point on, she leveled up fast and her strength, which was exceptionally to begin with, became more and more outstanding over the time. Her admiration for Metallikana grew more dominant too, until it turned into an obsession. When she was at level 5, Metallikana recognized her as one of the most promising bots in her squad. Not only her strength but also her loyalty stood out above the rest.

From this point on, Metallikana frequently trained her personally. She took a liking in Amaterasu and when she reached Level 7, which is the level that is necessary to get to a higher position than 'soldier' Metallikana appointed Amaterasu her assistant. (The level is important, because at this point, it is clear what direction a bots personality develops in and at this level it's possible to test how trustworthy they are and will be. Of course Level 1 Bots are the most trustworthy ones but they lack the strength and ability to make decisions on their own, so they can't be a leader) From this point on, Amaterasu started living in the Palace, the residence of everyone with a high military/ political rank.
Upon reaching Level 8, Metallikana asked Amaterasu whether she knows about that thing, people call love. And Amaterasu thought about this for a while, then asked if that was the feeling she had towards Metallikana, who just replied „Maybe.“ A little while later she asked her if she could describe those feelings in more detail and Amaterasu did. After that, Metallikana was pretty sure that Amaterasu was in love with her. Since she had feelings for her as well, they got together. It wasn't really a spectacular confession and surprisingly not really a lot awkwardness. Amaterasu wanted to be her girlfriend the whole time she just didn't know it was a thing. After all they don't teach the word love at the bot training camp. And since most of them didn't have a personality and usually only care about fullfilling their duties, nobody really talks about this. Metallikana’s way of thinking is pretty rational as well. If she'd be embarrassed because of love she wouldn't have become a squad leader.
This is how they got together. Amaterasu was excited about the somewhat different relationship she’d have with Metallikana from now on and over the emotional impact of finally achieving her dream, she reached level 9.