Sherl O.C. Kholmes* is a dog appearing in Layton's Mystery Journey: Katrielle and the Millionaires' Conspiracy. He is the assistant dog of Katrielle Layton, but he suffers amnesia and only seems to know the fact he probably was not a talking dog.
Sherl first meets Katrielle shortly after she starts her new detective agency. He immediately decides to test her by giving a puzzle for her to solve. After she solves the puzzle, Sherl explains that he has amnesia and would like Katrielle to find out who he truly is. Since he does not remember his own name, Katrielle names him "Sherl O.C. Kholmes", after the famous detective Sherlock Holmes.
- Sherl resembles a Basset Hound.
- Due to Sherl's ability to talk, it is speculated that he may be related to the "Subject" animals in Professor Layton and the Unwound Future. Additionally, it is also speculated that he could be Subject 2, since Subject 2 was never shown or mentioned, and Sherl mentions the only memory he has is an explosion, which did occur at the end of Unwound Future. This is, however, quite unlikely, unless the experiment would also significantly increase his lifespan.