Kaiman (カイマン, Kaiman) is the 1st episode of Dorohedoro anime series.
A door, created by the magic users, links both the human and the magic users' worlds together at Hole, in order for the magic users to practice their magic on humans. Kaiman is joined by Nikaido in search for the magic user that turned Kaiman's head into a lizard's—by killing every magic user they run across that aren't them. Inside of Kaiman is a mysterious man that seemingly knows who the magic user is that did turned Kaiman's head into a lizard's. Now, two magic users are having a practice session with Kaiman and Nikaido. Fujita tries to help save Matsumura, but he gets a broken finger from Nikaido and learns that his magic has no affect against Kaiman. Kaiman kills Matsumura because he is "not the one [who turned his head into a lizard's]," while Fujita escapes in a door to tell the tale.
While walking back from where they were, it's found out that Kaiman's last memory was of a guy's silhouette at the back of an alley. A magic user is then shown practicing his magic on a human and killing them, saying they have to complete their practice quota by killing one more "critter" in order to go back. Kaiman eats some gyoza at Nikaido's diner with her after a hard day and then vows to go after all magic users from tomorrow on. Matsurama has his funeral and Fujita meets with En afterwards and it's revealed that En doesn't like Hole at all. En also says Kaiman has another kind of magic already.
Then Kaiman gets a part-time job at a hospital and has to help patients affected by the magic users. He's joined with Nikaido and he freaks out when he realizes that he might have to always be on guard forever if there's no magic users there. The doctor shows up with a patient rushing through them and starts operating on them on a hospital bed with Kaiman. The patient was turned into an insect by the same magic user and the patient starts to have a spasm, but Kaiman isn't paying attention. Afterwards, Kaiman wants to go to Nikaido's diner to eat.
Nikaido's diner is in the worst spot of the city, where lots of magic users gather. Upon arriving at her diner, she is met with a magic user that's starving. As he's eating, they get to talking and Nikaido makes fun of the "shitty magic" she saw from a victim of a magic user to the guy eating. While she's talking it up, the magic user is revealed to be that same magic user that did that to all those victims.
It cuts back to Fujita and he can't go through a door on the other side because it's blocked off. Fujita then gets called by En and orders him to go on a mission to bring back Kaiman to him because he's killing his people. But he says not to use his gun he has, as it's not a magic user's manners to use it. But, Fujita doesn't care and vows to kill Kaiman and Nikaido.
Kaiman gets done with work and starts heading off to the diner. Immediately when he walked in it, something feels strange to him because there's usually a beer ready for him. He sees Nikaido slowly being turned into an insect by that magic user and the magic user says he's about ready to head back, almost completing his practice quota. Kaiman is fuming at him and starts to walk to him, getting magic on him but to no avail. Kaiman kills the magic user right there very quickly.
En and Fujita are back and En gives him a magic encyclopedia that has suspicious people in it. En wants Fujita to bring everyone in it back to him. While Kaiman and Nikaido take a picture together, trying to get a picture of the man inside Kaiman too, a door opens up near them. They encounter it and fight with a magic user there. Fujita opens a door amidst the fight, right on top of them. While Kaiman has the girl in his mouth, Fujita yanks her back in the door and effectively rips her face off.
Kaiman has the same nightmare every night about him dying and the man inside of him walking away from out of him. Two cleaners show up and one killed seven people in Hole, and the other didn't want to kill them that day, but only because those people had no important lives and are dumbasses.
- The ED song, "Who am I?" by (K)NOW_NAME, has magic doors open like the door animations of Resident Evil.