Fafnir

A dragon from another world (male). In his human form, he transforms into a young butler with long hair, narrow eyes, and round glasses, based on a photo given to him by Tohru. When he first visited Kobayashi's house, his monstrous appearance was his own interpretation of a "humanoid" form. As a dragon, he has a face with two pairs of single eyes like a spider, jaws lined with worm-like fangs, bat-like wings, tentacle-like legs reminiscent of Cthulhu, and often emits miasma from his entire body.

He has a difficult personality, always maintaining a perpetually displeased demeanor. His name means "the one who embraces," and he has long been guarding treasures deep in a cave, often being labeled a "recluse." He tends to keep a distance from humans, claiming to be "the dragon who trusts humans the least," and is known for his unfriendly behavior and sharp, dangerous remarks. He initially fought with Tohru when she tried to use his cave as a sleeping place, but they recognized each other's strength and became friends. Like Lucoa, he has a deep bond with Tohru, who informed him of her survival after escaping to the human world. Although he doesn't actively seek out other dragons, he is sociable enough to join in if invited. He shows clumsy care for those he trusts and has a surprising enthusiasm and initiative for things that interest him, including a fondness for sweets.

Although he doesn't belong to any specific dragon faction, he admits that his nature aligns him with the Chaos faction. His power as a dragon surpasses Tohru's, and he specializes in curses that can make humans sick. His pride as a dragon is extremely high, and his principles and beliefs as a dragon have influenced Tohru, leading her to seek "freedom."

Invited by Tohru, he came to Kobayashi's house and became interested in the game Takaya and Kanna were playing. Soon after, he decided to live in the human world and was given the name "Takeshi Oyama" by Tohru. After various twists and turns, he ended up staying in Takaya's room. Since then, he has been rapidly influenced by Takaya's otaku hobbies, immersing himself in online games day and night, visiting Akihabara, attending voice actor events, and participating in summer Comiket, where he failed to sell a single book but became determined to try again. He is thoroughly enjoying his otaku life in the human world. Despite warning Tohru about being too influenced by the human world, she retorts that he is the one who has changed the most due to his otaku transformation.

He is skeptical and negative about dragons and humans living together, and even despises the idea of superior dragons being influenced by humans. However, he gradually becomes interested in the bond between Tohru and Kobayashi and decides to live with humans to understand what it is. While he acknowledges that he can understand human interactions, he still believes they are dangerous and maintains his stance as a dragon. However, Takaya has noticed that he doesn't entirely dislike being part of the community centered around Tohru and Kobayashi.

He allows Takaya, who is becoming his roommate and partner, to call him by the unique nickname "Faf-kun," despite the risk of forming a strong master-servant relationship. He is also relatively comfortable with Kobayashi, who is adored by the dragons, and she sometimes jokingly calls him "Faf-san."

Anime version: He first visited Kobayashi's house in early spring (during the cherry blossom season) and started staying at Takaya's place in late spring (before the rainy season). Like Lucoa, his dragon form is depicted in a deformed silhouette in the opening animation. His daily life with Takaya is shown, revealing his subtle care and trust for Takaya through his indifferent attitude. In his monologue, he states his belief that "there are two types of humans: 'hits' and 'misses.' 'Misses' are obvious at first glance, and 'hits' can be recognized over time, but it's a waste of time to spend that much effort on humans." However, he acknowledges Takaya as a "hit."

Spin-off: In "Kanna's Daily Life," he is fully immersed in otaku culture, showing a particular obsession with magical girls. He also demonstrates a relatively mature approach to dealing with Saikawa and other human children who are with Kanna.