Loewen, also known as Roen, is a supporting character in Dance with Devils: Fortuna. He initially appears as a small Pomeranian dog that frequently accompanies Rem Kaginuki and the other devils, often lounging on the student council's couch and appearing harmless. In his dog form, he is laid‑back and unassuming. However, Loewen possesses the ability to transform into a human boy with short blue hair and blue eyes, standing 164 cm tall and weighing 51 kg. This human form is that of a male teenager dressed in the school uniform.

His background reveals a deeper and more deceptive nature. Loewen was originally the pet of Rem Kaginuki and served the Arlond family, but he later betrayed them to become the loyal servant and watchdog of Lord Maksis, a powerful fiend. His primary motivation is to serve Maksis and help him regain his lost power. To this end, Loewen searches for the forbidden grimoire, a key to Maksis's restoration, while hiding his true allegiance. Throughout the main storyline, he pretends to be loyal to Rem and the other devils, but it is eventually revealed that he has been secretly working for Maksis all along.

In Dance with Devils: Fortuna, Loewen continues his role as Maksis's devoted agent. His key relationships are defined by this dual loyalty: he acts as a spy and watchdog for Maksis, while maintaining a facade of obedience toward Rem. His development revolves around the revelation of his betrayal and his unwavering dedication to his true master. Notable abilities include his shape‑shifting between a Pomeranian and a human, as well as his sharp instincts as a watchdog, making him an effective scout and infiltrator. Despite his small and relaxed appearance in dog form, Loewen is cunning and single‑minded in his mission.