Baldur Riefenstahl is a supporting character in the anime Endo and Kobayashi Live! The Latest on Tsundere Villainess Lieselotte. He is the cousin of Lieselotte Riefenstahl, the series' titular tsundere villainess, and serves as an apprentice knight. His serious demeanor and excellent martial arts skills define his professional approach, though he is also described as being somewhat "hard-headed" or stubborn.

In the story, an oracle assigns Baldur the important duty of protecting Fiene, a magically gifted commoner who becomes a central figure at the Royal Academy of Magic. This mission is a key part of his role, as he joins a team dedicated to helping his friends in danger. He proves to be a capable ally, proficient not only with the sword but also with magic, making him a strong asset in combat situations. As the narrative progresses, his protective assignment evolves into a genuine and significant romantic relationship with Fiene, who is later revealed to be his cousin as well, being the daughter of Lieselotte's late uncle.

Throughout the series, Baldur works alongside others to support the union of Prince Siegwald and Lieselotte, while also fighting against external threats such as the Witch of Yore. He makes a personal promise to defeat the Witch of Yore himself, demonstrating his courage and dedication. His relationship with Fiene deepens as they collaborate to overcome these challenges, and he is present for key story events, including the Festival of Gratitude, where he reaffirms his feelings for her. In a notable moment, his strong-willed and sometimes overbearing protectiveness leads to a humorous confrontation where Fiene physically asserts her own independence, showing that his stubbornness is matched by her determination. His abilities as a skilled fighter and magic user, combined with his serious and loyal nature, make him a reliable figure in the effort to change the tragic fate that originally awaited the characters in the otome game's storyline.