From a young age, Shin suffered from asthma attacks. After his treatment, he came to Minasato village to recover. During this time, Shin's parents hired Amaki to take care of him. Amaki ended up being the closest person to Shin from taking care of him. They always got along well with no shame about anything, even bathing together (when Shin was a child).
During the course of the game, Hiroyuki Nishimura meets Amaki after finding Shin sleeping under a tree in the forest and trying to resuscitate him. Erroneously, however, this moment is never revealed. It's shown that Hiroyuki met Amaki two days later but implies that he met Amaki previously.
After Hiroyuki forcefully tries to rape Shin, this incident lands Shin in a depressive state and Amaki quickly notices. Since he knows Shin's feelings towards Hiroyuki, Amaki calls him and depending on the player's actions (Raping Shin or Recapacitate) he will talk about a certain topic. If the player recapacitated, he will ask Hiroyuki to cheer up Shin and clear his thoughts. As Amaki is his caretaker, his opinions may unintentionally force Shin to take Amaki's decision which he finds unacceptable since Shin must make his own decisions. He later asks the player if Shin and Hiroyuki had kissed already, saying later that it was a joke but is clearly implying that he knows about the close relationship between those two. If the player chooses to rape Shin, he will call Hiroyuki to have a serious talk. He will try to say that Shin is making a hard decision and he cannot do anything about it. He, as his caretaker, can't get involved in Shin's desicions and will always try prevent anyone from hurting and confusing Shin, implying that he knows that Hiroyuki raped Shin. He then clearly asks Hiroyuki to never see Shin again, which he does.
Amaki is last seen in the goodbye party, preparing the event along with all Hiroyuki's friends.
He really worries about Shin's health and sanity but never involving a lot in his thoughts, never crossing the line. And he can be peacefully violent as he does in the Rape Ending, asking Hiroyuki to not interfere on Shin's thoughts and never actually see him again.
He has good manners, as well as Shin, the only moment when he's informal, is when he calls Shin as "he" or simply Shin instead of "Master".
Even if Amaki is considered Shin's butler and caretaker, he's actually more like a relative, even sometimes doing actions that go against Shin's orders, such as inviting Hiroyuki after Shin asked to never let Hiroyuki to enter the house ever again.
Amaki is always seen with his butler suit, a white shirt with a sleeveless jacket with a red ribbon and black slacks, as well as his glasses.
Physically he's in a normal physical state with no high attributions. His fur is completely white including eyebrows, cyan eyes, and a series of bangs on his forehead.
- Even if Amaki looks like young man, he's actually above 30 years old.
- Shamoji's sketches show that he's actually 32.
- Amaki has been the only character that the Dev Team actually did an interview with before releasing the patch.
- Amaki was the first character to be known by his name. As Ten Kodori was just named as The Captain.
- Amaki writes books and does paintings, is never mentioned in-game but he confirmed it on the Dev Team Blog.
- Amaki's parents were going to name him "Tsukuyo" before they found out he was a boy. Once they discovered his true sex, they kept the same kanji but used a different reading, "Tsukishiro".