Root Academy
Kaito Daimon (大門カイト, Daimon Kaito)
Voiced by: Shintarō Asanuma, Chiwa Saitō (young) (Japanese); David Wald (English)
Kaito is a high school freshman who enjoys solving puzzles, feeling insulted whenever they are used for hurting others as his parents were killed while attempting to solve a deadly puzzle. He carries the Solver title, 'Einstein'. One day, he discovers the Orpheus armband which attaches itself to his arm. Under high levels of stress, he enters a strange state that allows him to use his brain to its fullest potential and see the solution for any puzzle. Normally, the Orpheus armband glows in a bright golden light and shows Kaito the solution to the puzzle, after which he faints and is exhausted. As of the 20th episode, the armband has evolved along with Kaito (as observed by Rook). It now glows in a dark blue light and shows Kaito an almost apocalyptic future (including all of his dead friends), if he continues down a certain path. It is then that Kaito realizes that no one should get the "Divine Scrolls" sealed by Pythagoras that the P.O.G. wants. After the 23rd episode, the Orpheus Bangle shatters, but Kaito is still able to use his accelerated brain potential without losing his convictions.
Kaito does not seem to have many interests other than solving puzzles. As seen in the first episode, he will e.g. use school property (in that case school desks) to solve puzzles, if he can't "see" through them right away. His friend Nonoha scolds him for that and slacking off, not refraining from physical violence as well. Although it is still uncertain what kind of feelings he might have for her, Kaito cares a lot about Nonoha by not letting her come in harm's way. He even hides the fact that one of her friends, the kindergarten teacher Madoka, is in fact a P.O.G. Giver. Kaito is very outspoken about Nonoha's cooking, calling the "Nonoha sweets" "weapons of mass destruction", which causes Nonoha to punish him physically. As for now, Kaito is the only one who openly dislikes Nonoha's cooking.
Nonoha Itou (井藤ノノハ, Itō Nonoha)
Voiced by: Kaori Shimizu (Japanese); Luci Christian (English)
Kaito's childhood best friend, who always accompanies him when he goes to solve puzzles. She possesses great strengths, excelling at sports, and has a photographic memory, though she is not too good with actual puzzles. She often makes sweets that almost everyone finds delicious but Kaito is incredibly fearful of. After helping some kindergarten kids during a puzzle, she ends up with the title 'Nightingale'. This is a shock for her, since she sees everyone with a title as a "weirdo".
Throughout the series, it is heavily hinted that Nonoha has feelings for Kaito. She does not hesitate to stalk Kaito when there is another girl or woman involved. For this purpose, she always forces Gammon to tag along. However, she does not admit that fact to herself, often claiming it has nothing to do with her. She is also somewhat of a tsundere-type and takes her frustrations out on Kaito, mostly, when he insults her cooking.
Gammon Sakanoue (逆之上ギャモン, Sakanōe Gyamon)
Voiced by: Jun Fukuyama (Japanese); Christopher Patton (English)
A red haired Solver with the title, 'Galileo'. He solves puzzles for money purposes and is often trying to get ahead of Kaito in order to claim the purported treasures offered by the POG. He appears to have a crush on Nonoha and even enters a cross-dressing contest to show her his feminine side. Gammon has a very competitive rivalry with Kaito. He calls him "Bakaito", a combination of Kaito's name and the Japanese word "baka", meaning idiot (The English version uses "Daimoron", a combination of Kaito's last name and the word "moron'). He and Kaito seem to have quite a few similarities, their hot temper being the most obvious. He has shown on many occasions his ability at solving puzzles is way above many others', and can easily spot what even veterans might not see. For example, he was able to pinpoint that Kaito did not make a mistake during the battles with Freecell, and improvised accordingly. It is noted that he seems to be on par with Kaito, except when Kaito's rate of thinking is accelerated by the Orpheus Bangle.
Gammon is always seen with his leather jacket and pants, giving him a delinquent appearance along with his hairstyle and his way of talking. He also rides a motorcycle.
Upon realizing (after a plot by Rook to separate Kaito from his friends) that Kaito is on another level than him, Gammon does not simply cope with that by distancing himself from Kaito (like Cubic and Ana). After the P.O.G. finds out that he is in fact "Chido Setsu", a mysterious Puzzle Giver from a magazine, Gammon is invited by Himekawa Elena to join them. He eventually passes the test by Bishop and is invited by Rook to join him in the quest of solving the "Puzzle of God". It is then that Gammon makes a radical change in his personality. What used to be a competitive rivalry between him and Kaito turns (seemingly) into pure hatred. Gammon does not want Kaito to solve the "Puzzle of God" as he intends to do it for himself and prove to everyone that he is superior, both as a Solver and Giver. His true motives are yet to be revealed.
After engaging Kaito in a deadly puzzle for the sole purpose of crushing him, Kaito makes a mistake (after seeing the possible future) and is about to kill him, before being called back by Bishop, much to his dismay. It proves his resolve, however Rook and Bishop still remain doubtful of his loyalty towards the P.O.G. (as he is actually a Solver as well) and true motives.
Cubik Galois (キュービック・G, Kyūbikku Garoa)
Voiced by: Kōki Miyata (Japanese); Shannon Emerick (English)
A young boy with the title of 'Edison', who is often inventing various robotics. He is often more fascinated by mathematics as opposed to puzzles, though he takes interest in Kaito after witnessing his Phi-Brain in action. At first, he appeared to be self-centered, however this resulted from him being too young to understand the full extent of some of his actions. Nonoha calls him "Ku-kun", which is quite a common practice in Japan but makes various puns (like with the character Q from the James Bond series). He is fiercely loyal to Kaito and uses his gadgets to aid him as much as possible.
Ana Gram (アナ・グラム, Ana Guramu)
Voiced by: Satsuki Yukino (Japanese); Brittney Karbowski (English)
A rather effeminate cross-dressing boy with a knowledge of famous paintings who often enjoys painting himself. Ana also wins a cross-dressing contest of the school, without even entering. He supposedly has the ability to communicate with the spirits of those who created puzzles. He is a Solver with the title of 'Da Vinci', his name being a pun on the word anagram. He has an elder sister named Eve, who seems to have a connection with Mizerka from the Orpheus Order.
Souji Jikukawa (軸川ソウジ, Jikukawa Souji)
Voiced by: Akira Ishida (Japanese); Blake Shepard (English)
He is the president of the student council as well as the president of the puzzle club. He is mostly seen smiling around others (except the headmaster) and likes to drink boxed apple juice with a straw, which he states is his treasure. Initially, he was a Solver with the title of 'Newton' but was unable to obtain the Phi Brain in his freshman year. The headmaster introduces him to the P.O.G., where he became known as a Giver under the name of 'Minotaur' which was first hinted in the first episode. But this turns out to be another disguise, as he is in fact a member of the P.O.G. Section Φ. It is revealed that he despises the direction of the new P.O.G., especially the new Chief of Headquarters, who just use the puzzles as a means to commit murder. To prevent this, he hacks into P.O.G.'s server once, to help Kaito and give him the necessary information to solve the puzzle and save Nonoha and himself.
Souji is very worried about the well-being of his underclassmen, especially Kaito and his friends, as he vows to himself to guide them to the Puzzle of God. He is well respected within the student body. Even Kaito acknowledges the fact that Souji was able to turn an ugly puzzle into a beautiful one within seconds. Being unable to figure him out, it is hinted that Kaito starts suspecting Souji of being involved with the P.O.G., as Souji was the one who gave him the pager, at the end of the ninth episode.
Souji has not fully accepted the fact that he was rejected by the Orpheus Bangles yet, shown when the Orpheus Order made snide remarks about him not being qualified to be their opponent since they only do battles with children of Phi Brain.
Other students
Tamaki Chieno (千枝乃 タマキ, Chieno Tamaki)
Voiced by: Rina Satō (Japanese); Carli Mosier (English)
Root Academy's student council vice president who has a crush on Souji. She is temporarily manipulated into being a member of the Orpheus Order when she thought Kaito was standing in the way between her and Souji, being given an Orpheus Earring, which later breaks when Kaito solves her puzzle.
Airi Mizutani (水谷 アイリ, Mizutani Airi)
Voiced by: Mai Goto (Japanese); Cynthia Martinez (English)
A student at Root Academy. She is one of the members of the Puzzle Club. When Airi was little, she knew how to solve puzzles; but for some reason, she can't anymore. She is also pretty clumsy, e.g. falling on the stairs and dropping things in the cafeteria while carrying food. Just like Tamaki, she is also temporarily manipulated into being a member of the Orpheus Order, and her personality changes from the clumsy, cheerful girl into princess-like. However, her Orpheus Ring breaks later when Kaito solves her puzzle.
Naoki Takeda (武田 ナオキ, Takeda Naoki)
Voiced by: Masahito Yabe (Japanese); Clint Bickham (English)
A member of Root Academy's Puzzle Club who is constantly challenging Kaito to Sudoku puzzles.
Yuuichi Aizawa
