Quite possibly the best and most reknown fighter of all the schools is a red haired girl, solely referred to as the Red Lion. But as the Red Lion suddenly disappears one day, we find that's only the beginning to the trials of real "Red Lion".

The Continent of Song is in chaos. The sinister secret society known as Demon Card is using the power of Dark Bring to destroy everything in their path.

The only things capable of stopping Dark Bring are the Rave stones. Unfortunately, the Rave Stones were scattered around the globe in an explosion 50 years ago, so now they must be collected by the Rave Master in order to stop Dark Bring once and for all.

This new task has been given to Haru Glory, a sixteen year old boy from Garage Island.

The World's fate now rests on the new, young Rave Master.

Asaka, the prison's nurse, is leaving her post to her gorgeous granddaughter Yuki, who will bring a lot of troubles and chaos in the life of the people around her, starting with detective Tatsumi, her childhood friend and now her neighbor.

From TokyoPop:

After 1000 years of peace, the wolf god Fenris Fenrir has been reborn. She seeks to find the reincarnation of Balder, the most beloved God, as the land of Midgard sinks further into anarchy. They are both key players in the coming of Ragnarok, the time when fate and free-will shall come into conflict as the very nature of the universe is forever redefined.

RilleL:
Based on norse mythology, ragnarök is the term for the end of the world. Christian equivalence would be the last judgement.

The popular Korean MMORPG "Ragnarok Online" was based on this book.

From Tokyopop:
On a world with no women, the surviving men have reintroduced the female in the form of an android. Called Marionettes, they are built to serve men and are limited in their interactions with humans. That is until a poor boy named Otaru Mamiya encounters a Marionette named Lime. Lime is a Saber model with a special circuit that gives her emotions. When Otaru awakens two more Saber Marionettes, his life as an 'average' man quickly becomes as extraordinary as the lives of his eager, busty new friends.

22 years ago a mysterious seismic phenomenon rocked the Yokohama district, thrusting it miles into the sky and effectively separating it from the rest of Japan. In the following years, a fraction of the newborns in this fledgling world began to develop extraordinary powers, each unique to the personality of the possessor. These mutated humans became known as Alters and were responsible for turning the former Yokohama into a chaotic wasteland. Now, as the former metropolis continues to re-build itself, the Alters have fallen into two camps: those who have joined HOLY, a dogmatic organization that hopes to re-establish order and morality, and those who wish to lord over the comparatively weaker humans. Only Kazuma, a powerful Alter who's really only interested in looking out for himself and an orphan girl named Kanami, stands between them, suspicious of both sides and unaware that he may hold the key to harmonious co-existence.

From Yen Press:

Millennium Academy is a school where elite vampires are trained to maintain balance in a world where humans and vampires, who possess far greater physical strength than their human counterparts, coexist. And commuting to this school is Aldred, the most distinctly un-vampire-like vampire to be found in the entire institution. But when Al encounters Kei, a human transfer student to the school, their destinies become intertwined, and the fate of their world as they know it comes to lie in their hands!

The story revolves around Tsukune Aono, a boy who accidentally gets enrolled in a school inhabited by monsters and demons. He quickly befriends Moka Akashiya, a vampire who soon develops an obsession with his blood, and later meets other girls who soon take a romantic liking to him.

On the once-peaceful planet of Industria, constant battles have been fought over control of the planet. Astro is a dim witted but kind boy who tirelessly works to feed his "family," a group of orphaned children. One day, after being fired from his most recent job, the prince of Industria, Bulge, appears in front of him. And even more shocking, Prince Bulge looks and sounds exactly like Astro! One thing leads to another, and Astro now has to take Bulge's place as the heir to the throne of Industria! Suddenly, he's faced with the task of bringing peace and harmony back to this war-torn planet!

- Red Hawk NEO

The Mana Tree, the giver of mana and life for the world of Fa'Diel, burned down nine centuries ago. A war erupted between faeries, humans, and others seeking the scarce power of mana that was left. When the war concluded, the drained Mana Tree slept and throughout the many lands of the world mana was stored in ancient artifacts.

Toto, and his pet Rabbi, have set out on an adventure to restore the world, and its mana, to its former self.

The Lands of Fa'Diel are populated with a large number of different creatures, including humans, faeries, demons, the jewel-hearted Jumi race, plant-like Sproutlings and Flowerlings, miner bears called Dudbears, and shadowy beings of the Underworld known as Shadoles. Fa'Diel is also the home of a host of anthropomorphic animals and objects, as well as monsters such as Rabites, Chobin Hoods, and Goblins.

Adaption of the PlayStation game of the same name.

From Tokyopop:

Fifteen years ago, a set of twins--a girl and a boy--was born to the king of Linevan. Shortly after their birth, a prophecy foretold that when the girl turned 16, she would bring about the end of humanity. To avoid this terrible fate, the king ordered the princess disposed of...scrapped!
She miraculously survived and was raised away from the kingdom that would kill her. But now she has turned 15, and the king's guards have caught wind that she's still alive...and they set out to finish the job!

(From Tranquil Spring) A comedy version of Simoun.

Welcome to the cursed island of Shina Dark. This island is called home by the dark lord Exoda C. Claw AKA Satan. He's as powerful a being as you could ever hope to meet. Feared and hated the world over for the infinite amount of atrocities he's committed. He's.....actually a really nice guy who just wants to chill out around the castle and relax... After a month long nap he awakens to find that the rest of the world has made up another ridiculous rumor and blown it way out of proportion and that has caused his little island to be crowded with a thousand beautiful girls meant to be his mistresses/sacrifices. Worse yet is that since they have set foot on his island they are all believed to be cursed and are now shunned by their homelands. What’s a couch potato Satan to do with 1000 women who wont leave? Who can say?

From Operation Boredom:

During an eclipse, demon Lord Exoda. C. Crown was revived. He is supposed to bring chaos and destruction to the world. The world is panicking, and as a sacrifice to the demon lord, they decide to send 1,000 girls to the demonic island, Shina Dark. However, in Shina Dark, all the legends are lies. Exoda does not sleep with 10 girls a night, and keep the others prisoners. He does not lust for girls, he does not want to cause mass destruction - he simply wants to live in peace. So when 1,000 girls suddenly show up in his island and refuse to leave, what will happen to Exoda, who simply wants to be left alone?

Tenchi Masaki is a shy high school boy, yet honest and hard working. He looks forward to living a basic humble life, taking over his grandfather's shrine. However, nothing is ever as simple as one would want, as Tenchi soon learns. A series of events beginning with the sudden appearance of Ryoko, the space pirate, creates madness in his home. Now he must figure out how to juggle 2 princess's, a space pirate, 2 galaxy police, the worlds most intelligent genius and a Rabbit-turned-Spaceship in his quiet country home.

From Turtle Paradise: After being shipwrecked on a remote southern island, Lina and Co. protect its townspeople from an attack by pirates…. But the island holds a deep, dark secret - and powerful magical forces are at work trying desperately to hide its past. The fate of the world once again rests in the hands of the over-bearing Lina Inverse… For better or worse! Join Lina, Gourry Gabriev, Zelgadiss Greywords, Amelia Wil Tesla Seyruun, and introducing Luke and Millena on a brand new adventure!

Heero attempts to live a normal life after the war. But his "peaceful" life is disturbed when someone manages to steal Wing ZERO. He rushes to search for it, and is then faced with an unlikely foe. On all accounts, Ground Zero can be considered a doujinshi due to its lack of consistency and subjected humor. However, it tackles deeply into the characters' morale and philosophies regarding war, peace, and of course, the gundams. Like Battlefield of Pacifists and Blind Target, Ground Zero are *possible* events that take place in between the TV series and the OVA, Endless Waltz.

Two years ago, the famous detective Narumi Kiyotaka disappeared, leaving behind only the words, "I am pursuing the mystery of the Blade Children." Now, his younger brother Ayumu is accused of murdering a fellow student, and begins to discover people with connections to the Blade Children all around him. The Blade Children were born cursed, and Ayumu may be the only key to saving them, but first they want to test him, by trying to kill him with everything they've got. All the while, it seems that Kiyotaka is manipulating events for his own unknown purposes. - From AnimeNewsNetwork Ongoing

From Tokyopop:
Renji is one of God's most powerful but overly violent angels. As punishment for going too far in the last battle against the demons, Renji is sent to Earth, where he must save 10,000 souls. Only then will he be allowed to return to heaven!

After meeting the enigmatic woman Hureika in a sideside village during her travels, the beautiful genius sorceress Lina Inverse’s fate takes a dramatic turn. Separated from her partner Gourry, she finds herself swept ashore onto an unfamiliar land. Faced with violent monsters, she is suddenly unable to wield her magic…. But her grand adventures only begin once she is saved by Lyos, a boy who claims himself to be the “Knight of the Aqua Lord”….

Alternate retelling of the Slayers TRY anime.

In the distant future, mankind has advanced into an age of technological supremacy, where magic is a lost art only mentioned in fairy tales and nursery rhymes. Living in such a world is Light Inverse, a youth who dreams of sorcery…. but suddenly, his home is attacked by demons! With modern weaponry proven to be ineffective against the monsters, all hope seems to be lost…. Until Lina Inverse and Gourry Gabriev are suddenly transported to the future from a mysterious shrine in their time. Can Lina bring magic back to this land…!? *Previously named as Slayers Future.