Dr. K (K博士 K bóshì) is the main antagonist of Changed. He is a scientist from before the events of the game, whom intentionally transfurred himself using his own drug that would allow its user to retain their memories and free will. He tries multiple times to contain the human, who he believes may carry the virus, from the outside world.
Dr. K is a bioengineer scientist, and as such, he operates with a cold and calculated behaviour - which is especially noticeable in the Special Edition where he completely disregards Puro's and the Human's attempts to leave out and interfering with him maintaining the probable safety of the remaining human population. He displays deep concern for the survival of humanity. This is in spite of himself no longer being human, which he mentions several times. He is committed to keep the protagonist in the Thunder Science facility to prevent the virus from spreading again.
He is a white wolf with red eyes, that wears a lab coat and a full face gas mask.
Despite K never being seen as human during the time the player character awakens - one can find a pile of photos showing him right after the transfur as well as his diary, where he describes the events of extinction, their experiments in the facility and his operation's success. The photos and diary can be found leaving the laboratory and if Puro successfully overpowers him. The photos can be found in his laboratory, past the computer and his diary in the next room with the thick glass pane - the very room he traps the protagonist inside while he goes to deal with Puro.
He is first found at the Secret Door and soon after, releases sleeping gas which tranquilizes the protagonist.
He plays an earlier role in the Special Edition, in which he leaves out tapes and sends broadcasts that can be listened to. In this remake of the game, K refers to Puro with names that are a bit more insulting than "failed sample". He also activates devices around the facility to try and stop the Human from proceeding, though, the Human successfully and repeatedly foils these obstructions.
- Despite his antagonistic behavior, K believes that he is just trying to do what is right. (it's implied in-game that the protagonist may carry the virus, and K is intent on keeping it inside the facility), meaning that he is more of an anti-hero/hero antagonist instead of a villain.
- DragonSnow confirmed that K wears a mask solely to suppress his newly acquired powerful sense of smell after he had undergone the transfur.
- DragonSnow confirmed on Twitter that K is a wolf.  (account terminated, verification required)
- How old is Dr. K? -??/??/21, 11:34 PM
DragonSnow4: Almost 30 years old, 6:47 PM, Twitter
- The main reason is that he is not used to such a keen sense of smell after transforming, so he put on a mask to make him more comfortable (Steam Community, "Spoiler questions.", December 7, 2020)