TV-Series
Description
Isolde Brach is a student who appears in a single episode of the series, set within the confines of a Catholic all-girls school where Fujiko Mine has taken a position as a teacher. On the surface, Isolde is depicted as a quiet and bookish transfer student who quickly becomes the target of affection and jealousy among her peers. Her most notable personal possession is a pendant left to her by her late father, an item of great value as it holds the key to deciphering a set of indecipherable research papers.

Within the school's idyllic atmosphere, Isolde is shown to be captivated by Fujiko Mine, who charms both the faculty and the student body. This admiration makes her a focal point of Fujiko's scheme, as the master thief uses her adult charm to get closer to Isolde and gain access to the coveted pendant. After an incident where jealous classmates punish Isolde by cutting her hair, she flees to Fujiko, leading to a moment of seduction orchestrated by the teacher to further her own goals.

However, the character's role is complicated by a significant deception. The Isolde Brach who interacts with Fujiko and Lupin is actually a disguise worn by Oscar, Inspector Zenigata's dedicated assistant. Oscar assumes the student's identity as part of an elaborate trap designed to capture both Lupin and Fujiko, replacing the unsuspecting schoolgirl to get close to the thieves. This revelation reframes the narrative, turning the apparently innocent student into a key component of a police sting operation. After the scheme unravels and Fujiko outwits Oscar to secure the pendant's code, the true Isolde fades from the story, her primary narrative function being as a pawn in the ongoing cat-and-mouse game between the series' main characters.

Given her limited appearance as a plot device within a single episode, Isolde Brach does not have a character arc or notable abilities of her own. Her personality, as presented before the reveal, is that of a shy, love-struck teenager, though this portrayal is ultimately an act performed by another character.