At first sight, Sana is a normal girl. She lives with her grandfather, Zouroku the florist, and while she may be a bit sheltered and not quite good at socializing, she is still a cute little girl. But the truth is that she isn’t Zouroku’s granddaughter: she is an escapee from a secret lab. Sana is part of a group of children who can access “Dreams of Alice”, a special power that allows them to alter reality. The children were kept locked up and experimented on, but Sana, the most powerful of them all, decided she wanted to be free and escaped.

Sana is a very good example of a mystery lead that is the mystery herself. Where did she come from before she was captured by the agency that experimented on her? Why did she, among all the other children, want to see the outside world when everything she wanted was at the tip of her hands anyway? Why did she wait to escape and let her captors live, when her powers allow her to rewrite reality as she wishes? This is what drives the story, and what makes Sana so interesting as a lead.

Ougi Oshino is a new exchange student in Koyomi Araragi’s classroom, and that alone makes her somewhat intriguing to everyone in the school. However, the fact that she has found a classroom where the maps say there’s no space for a classroom and that she claims to be the niece of a man who has no family at all makes her more special. To make things even stranger, she knows a lot about Araragi’s past, including the fact that he’s part vampire, and more than once, she seems to be the one behind every misfortune that Araragi faces during the school year. So… who is Ougi Oshino?

Owarimonogatari is the final chapter of the saga started in Bakemonogatari, and part of the Monogatari Series that deals with all the adventures of Koyomi Araragi. However, this time, he takes a second seat to Ougi Oshino who is not just the mystery to be solved, but the lead character who pushes him to investigate the school's mysteries and, in a way, the reason why she exists. This makes her a very interesting lead because she is not only the main character but also, as we discover at the end, the main antagonist. And that is why she absolutely deserves to be on this list.

We know that you're probably wondering how is Kakgurui a mystery since it seems like a pretty straight forward premise: Yumeko Jabami is a gambler addict who ends up in a school where everything is up for a bet. Case closed, right? Well, no because there’s a lot to be said about the Hyakkaou Private Academy and their strange way of preparing their students for the real world. And even if the Hyakkaou Academy doesn’t seem that mysterious to you, there’s also the strange Momobami family clan, that seems to control everything, and how they are connected to Yumeko. And where did Yumeko get three million yen to carry around with her on the very first school day?

Kakegurui is a very curious case where the mystery is not the plot but the characters. Yumeko is the most intriguing of them all, but she’s not the only student with skeletons in their closet and weird family relations. We get Kirari, the Council President, who seems to enjoy the idea of her whole system being destroyed as long as she gets to have fun, and her twin sister, Ririka, who hides her face behind a mask and seems the exact opposite of her sister, for example. And so, we include Yumeko since she is the lead lady in a group of mysterious ladies whose story is still not fully disclosed.

Ruka is a very normal girl, with ordinary friends and hobbies. That is, until the day she meets two strange kids, Umi and Sora, during her summer vacation. From then on, she loses all hope of a normal vacation, as she ends up involved in figuring out who her new friends are, and exactly what their connection to the Sea and its creatures is. And as she delves deeper into the mystery, Ruka also learns more about the people in her life and how much she can trust others.

Ruka is different from the previous entries on the list because she’s not part of the mystery that is presented to the viewer but the one who represents the viewer during the story. She is the one who asks the questions we want answers to and who starts figuring out what’s going on. While her role in the movie can seem cut short for time, she is an amazing lead who deserves to be celebrated.

Sakurako Kujou is a gorgeous, intelligent woman. She only has one defect, as far as both her “assistant” Shoutarou Tatewaki and fiancée Naoe Arikawa are concerned: She is far too interested in bones. Human bones, to be precise, as she’d love to have some for her already big collection of animal remains that she has painstakingly reconstructed using her knowledge as a genius osteologist. It’s not that she doesn’t understand that people would be upset if she kept the skull of their dearly departed, it’s that, ultimately, she doesn't really care. The only thing that distracts her from the bones in question is figuring out how the bones came to be, well, bones. And so, she and Shoutarou end up helping the Hokkaido Prefectural Police to solve more than one case.

Sakurako is a classic mystery lead: She’s an amateur sleuth who, due to her particular hobby, happens to be a better investigator than the local police. When not trying to keep the bones of the victim of the week, she’s a very straightforward person who claims to not have any emotional ties, but she is quite warm toward both Shoutarou and her housekeeper. Also, despite her love for skeletons, she despises suicide and won’t let anyone die if she can help it.

Shiki Magata has lived most of her life in complete isolation since she was 14 and was declared innocent of the murder of her parents. She's a scientist who loves logic and research but also prefers to have her laboratory completely empty. There's not much sympathy to be found within her, and during the trial for her parents' murder, she was almost called a psychopath, which is why it's better to leave her alone in her lab.

But when professor Souhei Saikawa and his assistant Moe Nishinosono arrive at her lab, they find themselves facing a new murder, and only understanding Dr. Magata's past can help them figure out what happened in the present and decide what will come to pass in the future. Once again, the viewers get the chance to try to understand our lead character, who is the mystery herself. And when we figure out all the clues is when we need to decide: Is Shiki our lead or our antagonist?

Urban legends are the root of many mystery stories: Where did they come from? Are they based on reality or is it just a tale that grows and changes with every person that tells the story? The mysterious Boogiepop is one of those legends, as the girls at Shinyo Academy center tell stories about them. Some claim Boogiepop is a shinigami and murders girls when they reach the peak of youth and beauty. Others claim that Boogiepop is a guardian who keeps the academy safe. And only a few know that whenever Boogiepop is not active and protecting the school, they lay dormant in the body of Touka Miyashita, a very common student at Shinyo Academy.

On her own, Touka wouldn’t be an interesting character. She is the most normal girl in any anime series. With no special family connections, no supernatural or dangerous hobbies and even a completely normal boyfriend, she wouldn’t be intriguing even as the victim of the week. But with the revelation that she shares her body with Boogiepop, an entity so mysterious that even their gender is a mystery, she becomes intriguing, even more than Boogiepop themselves. Because while we would love to know who Boogiepop is, the question of why they are tied to Touka becomes more interesting as the series advances.

Emma is everyone’s favorite sibling at the Grace Field House orphanage. She loves all her brothers and sisters, her “mom” Isabella, and is working hard to have good grades in her daily exams in order to be a great daughter for whoever decides to adopt her. Mom Isabella even thinks that Emma would be perfect to become a future Mother of a similar orphanage, but there's one thing she didn't count on: Emma's unending love and curiosity. Because when one of her sisters is adopted and forgets her plush bunny, Emma goes to give it to her and discovers the truth behind Grace Field House: It's not an orphanage but a farm, and those who are "adopted" are in fact killed and sold as meat to demons.

One would think that with the truth behind Grace Field House being revealed on the first episode, Yaukosoku no Neverland is not much of a mystery. But as the series advances, there are a lot of secrets for Emma and her friends to discover, and each time they find an answer, more questions appear. Emma's never-ending curiosity and her strength of spirit make her the perfect lead to solve the Grace Field House's mystery.

The Abyss is a deep and mysterious chasm that seems to have no end. Those who go past the fourth level will never return to the surface, although communication is still possible between the lower levels and the surface. And while people know that going into the depths of the Abyss means that they will never come back to their loved ones, Divers still go down to try to solve the mystery of its curse. Riko is just a Red Whistle, a rookie Diver, who dreams of becoming a White Whistle like her mother and meeting her in the Seventh level.

Riko is a very cheerful girl despite her troubled past. She died at birth and was brought back by an Abyss relic, which may explain her obsession with understanding it and her mother's choice to leave her behind to explore the deeper levels. It's heartbreaking to see the dangers she puts herself in, but at the same time, it's impossible not to cheer her on as she tries to reach the seventh level of the Abyss and her long lost mother.

Charles D’Eon de Beaumont and his sister, Lia de Beaumont have been working for the French government for many years: He as French secret policeman, and she as a spy in the court. So when Lia’s body appears in the Seine River, he wants nothing more than to find who is responsible for her death. This becomes a lot more complicated when Lia’s soul decides that she’s not going to leave her younger brother without protection and she needs to avenge her own death so she simply possesses Charles’ body in order to achieve all her goals.

Le Chevelier D’Eon has everything that a great mystery anime needs: A terrible murder, an ancient conspiracy, courtly intrigue and a stubborn detective who will stop at nothing, not even death. Lia, for her own part, is an incredible lead, not just because she's loosely based on a real person (Who crossdressed to be a spy for the French government at the end of the 18th century), but also becuse her motivations and her determination not only to solve her own murder but to also serve her country even from the beyond make her an unforgettable character.