Klaud is a vampire with plain features, jawlength, messy black hair, green eyes, and thick stubble on his chin.
In 150,081 CMT, Klaud woke up in a trashed apartment in the City at Night and reflected on his vampiric nature. He then heard what sounded like a military general on the radio state that aliens from Beta Centauri were invading their planet, which was followed by a TV anchorman mentioning "dangerous sea creatures", so Klaud panicked and assumed that the end of the world had come. He sarcastically shouted that "Cthulhu [was] rising", gathered his things and ran out into the street in search of help.
Klaud walked down the street and came across a large puddle of blood on the doorstep of an opulent mansion. None of the city's passing security drones seemed to notice it or care, so Klaud decided to investigate it himself. He found that the mansion's door was unlocked, so he proceeded inside and followed a trail of blood to its owner, a vampire who had been seriously injured. The vampire informed Klaud that Klaud was "Ortenrosse's Gambit" and that "Ortenrosse" must have sent Klaud to the city to find the Grimoire of Thade. Klaud could not recall these terms in his amnesic state, but the vampire reassured him that they had allies who could help them: Kay Faraday and Viola Cadaverini, except something had befallen Viola that had taken her out of commission. Lastly, the vampire told Klaud not to worry because he would regenerate his injuries, but warned him not to trust "Valdamjong" before he slipped into unconsciousness. Klaud opened the door of the mansion to leave, but paused when he saw Ta'harok in the middle of the street. He decided to sneak past him into a nearby alley.
The Night of Wallachia then appeared in front of Klaud and seemed to tell him that he was destined to become a Dead Apostle Ancestor. He also warned Klaud not to endanger the Masquerade, but Klaud ignored him and sang "Masquerade" from Phantom of the Opera instead, so Wallachia gave up and disappeared. Klaud then wondered aloud how he could escape the "weird" city, so Kay Faraday took the opportunity to reveal herself. Klaud was shocked by Kay's sudden appearance, but calmed down when she introduced herself and recognized her name as someone who was supposed to be an ally to him. Klaud was taken to a boarded-up door further down the alley which Kay transformed into an elevator with a key-like artifact. Kay and Klaud both entered the elevator and took it to a tunnel beneath the city that led them to a rough-looking vampire hideout. Kay told Klaud that he needed to wait there for a "Local Supervisor" to arrive, which made him roll his eyes at the fact that vampires had "supervisors", but decided to wait regardless.
- Klaud Ortenrosse shares the same surname as Trhvmn Ortenrosse, a character in TYPE-MOON's Nasuverse.
- No other connection between Klaud and Trhvmn Ortenrosse has been established, but it is possible that Trhvmn was the Ortenrosse who was referred to in the phrase "Ortenrosse's Gambit", because it would not make sense for Klaud to be his own "gambit".