The famous London detective who butts heads with Lupin.
- Ambiguously Related: His exact relation to Holmes III and Sherlock Holmes III, if any, are unknown.
- Worthy Opponent: Unlike Holmes III, Lupin admits to viewing him as a worthy rival and successor to the original Holmes.
John H. Watson's daughter, who suffers from traumatic memory loss caused by seeing Lupin.
- Kid Detective: she's pretty good at deduction. Not surprising, given her guardian.
- Like Parent, Like Child: She starts to develop some very promising sleuthing skills. Before long, Holmes basically has her as his partner.
- Trauma-Induced Amnesia: Seeing her father being killed by Lupin left her with deep emotional scars, and she starts having panic attacks whenever she sees Lupin. However, her memory is incomplete. Lupin truly didn't kill her father but someone else. What's more, she actually remembers who it was when things start to clear out, and that someone was Lestrade.
A renowned Scotland Yard inspector who works with Sherlock Holmes on the Raven case.
- Big Bad: He is the true culprit behind Watson's death, having him killed.
- Driven to Suicide: After learning Raven had disbanded before he killed Watson, he killed himself via explosives.
Sherlock's former partner, who was killed in an alleged murder by Lupin.
A newly appointed inspector who teams up with Zenigata and Yata. She was one of Tomoe's sleeper agents.
- Ship Tease: She and Yata slowly start to get into a relationship.
A young man with a mysterious past and interest in Lupin.
A flower girl Lupin meets in New York while trying to infiltrate an auction, indirectly getting close to her and forming a paternal bond with her. In truth, she is one of Tomoe's many sleeper agents out to find and kill Tomoe for screwing her life.
Leader of the Mirage Women, and one of Tomoe's many sleeper agents.
A lady doctor who had saved Jigen's life and fell in love with him. She is also one of Tomoe's sleeper agents.
A popular fashion designer coming out of a five-year hiatus who enlists Goemon's help after saving him from drowning in the Arctic. She's also Tomoe's sleeper agent.
A former chief engineer and CEO of the security firm Wangtic in hopes to capturing Lupin with her highly advanced L System but is really secretly very much in love with him.
- Ambiguous Situation: Given later revelations, one has to question if her crush on Lupin is genuine or a result of Tomoe's manipulations.
The Republic of Cotornica's rising politician with connections to Tomoe, whom she thanks for her success.
An old associate of Fujiko and a devil-may-care con artist.
- Ambiguously Bi: She flirts with men and is later revealed to be pregnant and Fujiko, to the point that Lupin becomes visibly jealous. Also, her relationship with Fujiko sometimes comes off less like that of a former partner or friend, and more like that of an ex-lover.
- Oral Fixation: Rarely seen without a lollipop, apparently replacing her old smoking habit. Amelia suddenly having given up smoking is what clues Fujiko in that she's pregnant.
- Remember the New Guy?: She's Fujiko's former friend and partner-in-crime (literally), but was never seen or mentioned in any prior installment.
A young woman from Mitten village who comes to meet "Madame" (Fujiko) and proceeds to ship her with Jigen, Goemon, and Lupin.
- Connected All Along: She's eventually revealed to be one of Tomoe's agents.
- Shipper on Deck: She's smitten by Fujiko's beauty and quickly tries to ship her with Jigen or Goemon. Ironically, she finds Lupin to be an idiot not worth her time, at least until she finally learns about their relationship.
A young woman who travels to Revonland in the Arctic to learn about her mother, who died giving birth to Finn.
- Bastard Angst: It turns out that her father wasn't the man her mother fell in love with (Sean), but rather the Jerk Jock Allen who had assaulted her. When Finn learns this, she goes into shock, though Lupin arrives to calm her down.
- Death by Childbirth: Her mother died shortly after giving birth to Finn.
Lupin's former private mentor who taught him all about the art of thievery and made him call her "mother" as a sign of apparent affection.
- Ambiguously Related: Despite Lupin caller her his mother, they really aren't family by blood. This later gets complicated when Lupin is forced to fall into her brainwashing and he starts to defend the very idea that they're mother and child, though everything points out that they're not related. Still, Tomoe deluded herself into thinking they were mother and child anyway.
- Big Bad: Of the Witch and Gentleman arc.
- Manipulative Bastard: She mentored quite a whole deal of young women into becoming her sleeper agents all for the sake of keeping a tight leash on Lupin, whom she considered to be the world's greatest thief. She believes that controlling such a person makes her an indisputable mastermind capable of doing whatever she wants.
