is a Japanese manga series written and illustrated by . The series began serialization in Kodansha's Young Magazine the 3rd magazine in September 2014 and was later transferred to Monthly Young Magazine in 2021 before finishing serialization in 2022, and is being published in English by Kodansha USA. An anime television series adaptation produced by A-1 Pictures aired between January and March 2017.
Plot
The story takes place in an age where demi-humans, more casually known as "demis", have slowly started to become accepted into human society. Tetsuo Takahashi is a biology teacher who ends up teaching three such demis, hoping to understand more about them while also managing to catch their attention.
Characters
A biology teacher who is fascinated by demis and wants to learn more about them. He is occasionally referred to as "Iron Man" by his students, a pun on his bulky physique and his name. As he learns about demis, he starts to understand the problems they face, both as teenagers and demis, and strives to help them in any way he can. Takahashi is often the girls' go-to person due to his knowledge on demis and his kind and helpful nature. He has a guardian-like and caring relationship with the girls and is always looking after them for their well being.
A highly energetic vampire. She avoids biting other people's necks, instead drinking blood packs sent by the government and using blood substitutes like tomato juice. Contrary to myths, she loves eating garlic and merely dislikes bright lights and warm temperatures. Hikari has a twin sister, Himari who is human. Despite being the older twin, Hikari acts like the more child-like sister where as Himari is the more mature one. She occasionally has the urge to nibble on someone, usually her sister, to stop her teeth from itching. Despite her lackadaisical nature, she often strives to help others in need. Hikari's mother is a vampire and her father is a human. Hikari has a tendency to hang out in Tetsuo's biology room since it's cool and doesn't receive much sunlight. Her favorite food is liver and onions.
A shy dullahan whose head is separate from her body, which has a blue flame coming from where the neck should be. Since her arms are occupied carrying her head, which doesn't move on its own, she longs for contact with others (holding hands, hugs etc.) Kyōko develops a crush on Tetsuo, due to his kind and caring nature. She initially found it hard to make friends as people found it awkward to talk to her without bringing up her detached head in some way, despite her own acceptance of the concept and desire to joke about it. Incidentally, a medical procedure has proven she does possess a neck, which connects her mouth to her stomach and lungs, but somehow exists in "another space" and serves as a Wormhole between her head and body. After Hikari notes how awkward it must be for Kyōko to carry her head in one hand and school bag in the other to Tetsuo, he talks to the principal and the school allows Kyōko to wear a backpack for her convenience.
A timid snow woman whose body is always cold. She will sometimes spread cold air while experiencing negative emotions and is susceptible to heat. Yuki initially dislikes her demi nature, fearing that she could harm others or those around her, though Tetsuo manages to show her that the only things she can actually freeze are her tears and sweat. Hikari will often want to hug or hold onto Yuki due her cold body temperature since vampires don't manage well in the heat. Yuki also secretly a manga enthusiast and has a taste for multiple genres. After befriending Tetsuo, Hikari, and Kyōko, she begins to open up about herself and talk more.