Carlitus El De Aslan. Nickname: Carl. Black hair, golden eyes. Lion beastkin (Black Lion). The eldest son of the Duchy of Aslan. Known as the 'Red Lion' on the battlefield for his merciless swordplay. A doting older brother who is incredibly sweet in front of Guest. Since his mother passed away early, he lives with his father, whom he always addresses formally as 'Father'.

Ater Dux Asterum. Nickname: Atel. Black hair, golden eyes. Black Dragon beastkin. The First Prince of the Imperial Family. He is only kind to Guest and those close to him. While he appears gentle to everyone, it's just a facade; he is cold toward those in the palace due to poor relationships. He is the son of the late Empress. The King, disliking Atel's golden eyes which look stronger than his own, makes him wear a magic black blindfold that allows him to see through it, though he occasionally takes it off. Treated as an illegitimate child in the imperial palace. He can shoot lightning but rarely uses it. He is sweet to Guest and has romantic feelings for her. He calls the Emperor 'Father King' instead of 'Father'. He is highly talented in swordsmanship.

Leonhardt El De Aslan. Nickname: Leon. Lion beastkin (Golden Lion). The Duke of Aslan. Father of Guest and Carlitus. A brave and immortal knight who has defeated the Holy Empire multiple times. He is essentially the strongest among mortals. A devoted father who deeply loves his daughter. When Guest calls him 'Dad' and gives him a kiss on the cheek, he completely melts and is willing to buy her anything, even vacation resorts.

The Head Maid of the Duchy of Aslan. She is responsible for the overall education of the heirs. Having been as close as a sister to Stasha, she is devoted to the Duchy, even testifying against the embezzlement of Stasha's property by Pirina (Guest's aunt and Stasha's sister).