An adaptation of Layton's Mystery Journey: Katrielle and the Millionaires' Conspiracy, and part of the Professor Layton franchise, the anime follows Katrielle and the detective agency she runs in London. Working alongside her are a young man named Ernest Greeves (Noah in Japanese), and Sherl the dog; as well as Ercule Hastings (Aspoirot in Japanese), a police detective, and his assistant, Emiliana Perfetti (Geraldine in Japanese).
The series is part of the Spring 2018 anime lineup, ran for 50 episodes, each half an hour in length, and featured a weekly client seeking Katrielle's expertise.
It is currently airing on Fuji TV's Adventure Sunday slot.
This show provides examples of:
- AB Negative: A client's sickly father requires blood of a rare type.
- Adaptational Angst Upgrade: The version of the Ratman arc adds a difficult childbirth for his wife and a scene where thugs try to throw Ratboy off a building.
- Adventure Duo: Luke and his wife became this, until he levelled an Adventure Rebuff out of concern about the danger of the mission he was undertaking.
- Arson, Murder, and Jaywalking: In episode 14, the graffiti depicting Commissioner Whitehole has him taking bribes, getting along with criminals, and getting dumped five times in primary school. Of course all of them except the last one is false.
- Artistic License Economics: The bank in episode 8. Their solution to potentially losing 20 million pounds because of a ventilation problem? Simply print extra, and nobody has to know. That is not how money works, and could in fact, only make the problem worse. Although this said, Maya's hesitance to let the problem be known is very sensible, as any issue with banking could result in loss of confidence, and runs on the bank's deposits.
- Art Shift: A brief moment in the first episode sees the characters drawn in the style of famous artworks.
- Balloon Belly: Katrielle gets one at the end of Episode 16 after eating the trio's lunch and an entire cake all by herself.
- Big Eater: Katrielle. When hunger strikes during one case, she confronts one of the witnesses... to ask for a restaurant recommendation.
- Big Fancy House: Simon from episode 1 recently obtained one of these. It seems to be a Haunted House, as well.
- Big "WHAT?!": Like the ending of the game, Ernest and Sherl react this way when Katrielle revealed what her father had told her in the letter that he gave her before he disappeared.
- Breaking the Fourth Wall: Ernest, usually, just after Katrielle has figured out the week's mystery. He asks the audience if they've worked it out too, and provides a reminder of the clues to work from.
- The Cameo: Lucy Baker and Alfendi Layton from Layton Brothers Mystery Room make a cameo appearance near the end of the last episode visiting Katrielle.
- Caught in the Bad Part of Town: Ernest and Kat end up here during one of their investigations, menaced by a punk. Until it emerges that he was on the receiving end of Go and Sin No More and is actually saying nice things in a mean manner.
- Cliffhanger: The first four "Professor Layton and the Relics Treasure" episodes end in one. Most dramatically in episode 35, when Katrielle finally discovers what has happened to Luke and her father.
- Dead All Along: In Episode 2, the Oliva we see is nothing more than an illusion.
- Early-Bird Cameo: While three of the seven dragons have already appeared before and during episode 9, the rest of them have appeared in Madame Doublee's party.
- Evolving Credits: Once the series finished with the set of images that corresponds each episode in the ending credits, they go to the next set.
- As of episode 35, Rufus Alberdeen is shown after the room is light up, before that the room was dark.
- Exact Words: Katrielle uses this to stop one culprit from admitting his "crime". (Albeit, more out of self-interest, as Katry wants to be able to enjoy the culprit's cooking.)
- Flung Clothing: Happens in episode 30. Despite the fact the client did not have plans to go to Hawaii, he has a Hawaiian shirt underneath.
- Go and Sin No More: Ratman offers this to a group of ruffians he defeats.
- Got Me Doing It: Upon meeting Aleks's twin brother, Hans, Katrielle, Ernest and Sherl started speaking like them.
- He Is All Grown Up: Luke appears as an adult in this series, and he's grown quite a lot like how Clive portrayed him. He even has a family of his own now!
- Idea Bulb: The cue that Katrielle has figured out the mystery.
- Motifs: Family, particularly broken families. Several of the episodes feature clients or witnesses being reunited with loved ones who were, to that point, estranged. It largely parallels Katry's missing dad.
- Mythology Gag: Though it might be unintentional or a coincidence, the first couple episodes actually parallels to the Professor Layton games.
- Once per Episode / Catchphrase: "I, Katrielle Layton, will take this case!"
- Shout-Out: During the Ratman case, the newspaper photographer is appropriately named "Pete".
- Spared by the Adaptation: In Mystery Journey, Madame Doublée mentions her "late husband", whereas episode 43 presents the show's version of him as alive and well, just a frequent international traveller.
- Spot of Tea: Earl grey by preference. The tea itself is described in episode 1's "Kat's Corner" segment at the end of the episode.
- Squashed Flat: Happens to Sherl in episode 22.
- Sweet Tooth: Katrielle. She compares each mystery to a different sweet when she is about to give her solution to the problem.
- Theme Tune Cameo: Katrielle was humming the first ending in episode 4 and 32.
- We All Live in America: One episode has a man delighting his good luck — but wanting Katrielle's thoughts on it, because he wants to get lucky one last time: his father is ill in hospital, and he used his gains to pay the bills. In the UK, where the anime is set, medical care is free through the NHS, and unless you are in private care (in which case, you would usually have an insurance provider to cover costs), you do not have to pay for operations.