Atli Reginhard (アトリ・レギンハルト), mainly called by his first name in the series, is a legendary swordman and the foster father of Zelda. Atli is an Álfur who worked once in the court of Ygvarland, but retired due to "health reasons" (in truth, there was a scandal between him and one of his male students). He is the one that taught Zelda her fencing skills.
A very handsome man, Atli is slim with a youthful appearance. He is mostly seen wearing a hakama. In the manga it is presumed that his hair color is blonde like most Álfur, while in the anime it's light blue-gray. His eyes are blue and he uses glasses.
Atli is homosexual and is attracted to Naoya, easily getting nosebleeds in Naoya's presence, something that her foster daughter never notices due to her father complex. Atli raised Zelda since childhood, although it is never mentioned how they meet or why he decided to take care of her.
At 16 years old, Atli was already a legendary swordsman after he slayed an evil dragon by himself. At 20 years old, he was invited to Ygvarland court and remained there for two years when he retired from service to the kingdom due to health reasons (in reality, it was due to a scandal with a young boy who was his student).
When Judit was looking for someone to protect Rotte after she decided to leave Mercelída's castle, he first sought Atli, but Atli refused Judit's invitation. The young Zelda, however, became attached to Rotte and decided to take his place and become Rotte's guard.
Atli seems to be always calm and has an amicable disposition. He, however, loses his cool composure when he gets close to Naoya. Zelda can only see his manliness and remains oblivious to Atli's sexual preferences. In combat, Atli is a fearsome warrior who is capable of slaying a dragon by himself or sneaking like a ninja without making a noise.