An akuma is a soul which has been brought back to life through sadness and despair with the powers of Millenium Earl. Their mission is to terrorize the earth and all who dwell within it. The Black Order is a group of Exorcists that have sworn to cleanse the souls of the akuma, and collect the substance known as "innocence". This powerful substance can be used as an anti-akuma weapon, and ultimately can help destroy the evil Millenium Earl. Allen Walker is a young Exorcist who has the ability to tell who is human and who is an akuma with the help of his cursed eye. Together with the Black Order, Allen must find all 109 pieces of innocence to protect the world and defeat Earl.
Mai Taniyama is a first year high school student who lives a carefree life telling ghost stories with her friends. One day, she meets Kazuya Shibuya, the head of Shibuya Psychic Research (SPR); and together, she tags along to help him investigate paranormal activities in a haunted school building. His assistant Lin was hurt during an incident to protect Mai from danger, so what more can Mai do than to take the job as Shibuya's assistant? Along with a team of other ghost hunters, they will uncover the mystery of a strange case coming their way, while Mai starts to discover her own abilities.
Both D.Gray-man and Ghost Hunt are about exorcisms, have equally mysterious main characters, and very well thought-out plots. Allen Walker (D.Gray-man) is a very funny boy with a hidden past and an arm that has what is called an anti-akuma weapon to help him fight off evil; every time you think that he can't fight any longer he always seems to surprise you. Kazuya Shibuya (Ghost Hunt) is not very funny by himself, but when teamed up with Mai Taniyama he gains a somewhat sense of humor; he has a hidden past that is only known by his loyal assistant Lin. If you wind up liking one you will definitely like the other.
Fifty years ago, the Demon Stone and RAVE (two powerful artifacts) are broken and scattered throughout the world. The story follows the journey of Haru Glory; during his travels he meets many new friends and allies, and also enemies known as the Daemon Card. He will have to use the powers given to him by RAVE to defeat the Daemon Card and find the other pieces of RAVE.
In both D.Gray-man and Rave Master the good guys collect innocence/raves to fight the evil they oppose. The bad guys want to destroy or get them for themselves so they constantly send goons to fight the good guys. There are many dangerous battles, and as the times passes by the good guys gain more powers, become stronger, and make new friends.
Akari has always known two things: she’s a skilled fortune teller, and she has an uncanny knack for growing huge, healthy plants. But after experiencing a traumatic tragedy the girl soon discovers the true horror of the world: there exist evil spirits known as Daemonia that infect people’s hearts and grant their hosts wishes in exchange for a contract. After the wish is fulfilled, the human is turned into a murderous monster, and only Sephiro Fiore, a group of girls who wield the powers of the Elemental Tarot, can put a stop to them. As the bearer of the Sun card, Akari must join Sephiro Fiore and help take down those possessed by Daemonia, no matter the cost.
Each character in both of these anime are given some special power, by a Tarot card in GBI and "innocence" in D.Gray-Man. They are then thrust into a special organization in which they use these powers to kill evil beings that were once human, sometimes even humans that the character has loved. The way these people become evil beings is also quite similar, in DBI it is the despair and sadness of wanting a wish granted at the cost of their souls, in D.Gray-Man it is someone elses despair and mourning wishing to bring back the dead that turns the ressurected person into an akuma.
Nai’s friend Karoku is missing, and the only clue to his disappearance is a mysterious bracelet. One day while travelling, a young thief named Gareki saves Nai from a monster and takes an immediate interest in the trinket he carries, as it is the insignia of Circus, an elite group who travels the world capturing notorious criminals. Together, the two decide to track down Circus and see if they’ve taken Karoku, but luckily, the group finds them first. Unfortunately, they have no idea who Karoku is or why he had one of their identity bracelets, but in the hopes of getting to the bottom of the matter they offer their assistance. Now, Nai, Gareki and their new friends set forth to find Karoku, but with more questions piling up each day will it be possible to achieve their goal?
An invasion of mysterious forces that comes in the form a corruption of the existing world, fought against by people with incredible powers. The ordinary, familiar, and beloved turned grotesque. The eternal appeal of the Faustian bargain. Above all, the timeless power of regret.
In Amberground - a land of eternal night infested by giant armored bugs - a small group of civil servants known as Letter Bees carry out their daily job. Charged with delivering important letters, each Letter Bee is partnered with a ‘Dingo' to protect them and ensure their consignment safely reaches its destination. One day, a rookie Letter Bee named Lag Seeing and his Dingo Niche are given a special assignment: they must deliver a particularly important package to a former Bee. Accompanied by an old and rather smelly ex-Dingo called Darwin who is acting as their guide, the journey to the town of Silencio is set to be difficult and dangerous. Will the rookie Lag be able to deliver the package safely, and does he even know the true purpose of his delivery?
Though D.Gray-man is about an Exorcist and Letter Bee is about a delivery Boy, both series share a similar sort of darker tone. Both also contain some comedy as well as drama and a bit of action. If you liked the tone of one, then try the other.