He is the curator of the department of Asian Arts at the Louvre. He grants Rohan Kishibe authorization to see Nizaemon Yamamura's mysterious painting, Under the Moon. Gaucher accompanies the manga artist to the abandoned warehouse where it is stored along with Noguchi and two firefighters.
Gaucher is a man of average height and build with shoulder-length hair that he keeps combed back, which is wavier at the bottom. He has a beard that is darker on his chin and angled eyebrows. Gaucher wears a light-colored suit with a white buttoned shirt.
Gaucher is a cautious man who takes several security measures before allowing Rohan to see the painting. He has Rohan leave behind all of his personal items and assigns two firefighters from the museum's security services to accompany Rohan, as well as himself and an interpreter. He only allows Rohan to observe the painting for just five minutes to make sure nothing goes wrong.
He is also secretive, not wanting to tell Rohan about what part of the museum they are currently located at while they are traveling to the abandoned warehouse.
He has in-depth knowledge about the Louvre's history, knowing exactly when the Louvre was founded and why the Z-13 warehouse was abandoned.
At some point in his life, Gaucher was involved in a car accident which resulted in the death of a man.
Gaucher is introduced as the responsible curator for the Department of Asian Arts at the Louvre. He gives Rohan Kishibe authorization to research Nizaemon Yamamura's Under the Moon, but only for five minutes. He also asks him to leave behind anything he has. Surprised that the Louvre had a work of an artist he never heard about in the Z-13 section, which was long ago abandoned, he accompanies Rohan along with two firefighters of the security services and the interpreter Noguchi to investigate it.
When the group finally finds the painting, one of the firefighters has his skull pierced and is sucked into the darkness of the ceiling. Gaucher is the first to notice the ghost mob attacking them and attempts to call the police, believing them to be simple thieves, but is smashed against the wall and suddenly covered by tire marks across his body. Moments before dying, Gaucher recognizes a ghost as the same person who was killed in the traffic accident and is sucked into the ceiling's darkness. His body is never found, and he is considered missing afterward.
In the live-action film, Gaucher plays a more minor role and is given the surname "Bigotte". He is changed to the curator who purchased the black painting in the past, whereas Ryunosuke Tatsumi replaces the role Gaucher had in the manga. His employee number at the time was "0005431510".
A little over 20 years prior to 2023, Gaucher heads from France to Japan to purchase a few paintings from the storehouse of Rohan Kishibe's grandmother. Rohan hands the paintings over to him, and Gaucher thanks him before leaving. However, Gaucher then goes missing after storing Nizaemon's painting in the Z-13 warehouse at the Louvre.
- Gaucher was likely inspired by Fabrice Douar, the real life curator for Hirohiko Araki's exhibition in the Louvre. He also accompanied Araki during his tour into museum's basement.
- In the original one-shot, Gaucher went only by his first name. In the film adaptation of Rohan au Louvre, he was given the surname "Bigotte".