The sea in our world has been polluted. All sort of trash were thrown into the sea, making it unpleasant deep under the sea. One of the inhabitant of the sea, Ika Musume (Squid Girl) seeks to exact revenge on humanity for throwing trash into the sea. Clueless about the surface, she seeks to invade humanity alone, trying to rule over the world, only to find herself slaving away at one of the nearest beach-houses for breaking a side of its wall.

The St. Mikhailov Academy student Oribe Mafuyu comes across a mysterious silver haired boy named Sasha. He is a Qwaser, a being that draws power from Soma and is able to manipulate a specific element. And now, in the 21st century, the mystery revolving around an Icon turns the academy into the battlegrounds for the fight between the Qwaser!

When the last night of the field trip comes around, teachers will throw a party and become less mindful of the students. Whilst students use the great opportunity to run off somewhere, the night becomes a time when everyone can kick off their shoes.

Student Search Group Teacher, Natsukawa Hikaru, is in charge of finding delinquents truanting and is most commonly known to be dumb. However, on the hunt of such students, Natsukawa-sensei seems to have caught himself in trouble. Overseeing the innocent Natsukawa-sensei in trouble, illegal leave-taking student, Koga Takaya, comes to the rescue. Having finding an interest in the dumb-witted Natsukawa-sensei, Koga asks for a kiss in return. Not knowing Koga is actually one of the delinquents he is suppose to be looking for, due to his vacuity, Natsukawa-sensei is disturbed to the departed fact that Koga knows exactly who he is. Having become close throughout the story, will Natsukawa realize the fact that he is in love with Koga Takaya, or will his incompetency lead him to loneliness?

From the Mangaka, Takasawa Taeko, a story of love, angst, and drama is a must read that will have you hypnotized throughout the whole series.
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Contains four oneshots:

Side Effect (oneshot) - When Itsuki met Washinomiya-sempai, he was a post-graduate, and Itsuki was in the university he attended. Two years later, Washinomiya graduated and got a job, whilst Itsuki was still a student... so they lost contact.

Washinomiya found a job at the corporate headquarters of Tanzawa Pharmaceuticals. Wanting to be by his side, Itsuki becomes a guinea pig for Washinomiya-sempai by taking pills. Asking himself a question, Itsuki accidentally slips and awakens to him being shackled to Washinomiya-sempai's bed! In a story of desperation for each other, what will be the outcome, and what exactly are these pills Washinomiya-sempai is giving to Itsuki? Read and unravel the mysteries...

Sore Demo (oneshot) - Satoshi Ichirou begins training to be a teacher in two days, so he had to borrow materials from his friend (Itsuki). However, accidentally eating one of the pills Washinomiya created, the pill completely changed Satoshi into a female, only to have a lasting effect of six hours. Looking and thinking like a female, Satoshi is seen to be leaning on a display glass of a female jacket. The store manager sees the suspicious Satoshi and invites him into the store. After trying on an outfit, Satoshi pulls out his wallet to see if he has any money, whilst at the same time a movie ticket floats out onto the ground. Satoshi crouches down to grab the ticket, but at the same time, a man with boxes blocking his view from below topples over Satoshi. Who is this charming man, and what will happen between the two? It is definitely a must read, that will encase your heart to what is known as love at first sight.

Cigar Boy (oneshot) - Sugita Nobuyoshi (25 years old) is everyone's acknowledged lolicon, and he admits it himself. Going out and about from the office to fetch a carton of maisen, he is mistaken for an old man and is given a weird brand of cigarettes called 'Cigar Boy' from a mysterious kid who is a boy but happens to look too much like a girl. Not daring to smoke them, Sugita throws the packet away, but curiosity killed the cat and got the better of him. After taking a couple of puffs, a cigarette genie appeared from the smoke and announces that he will grant three wishes! Will Sugita wish for fame, wealth, and power, or will it be something that money can't buy, fame cannot get, and power cannot control: love? The intensity of the story will have every reader on the edge of surprise!

Dr. Vamp (oneshot) - Tanzawa Chemical Production Second Department new employee Okamoto, seems to be a bit lethargic at the moment. He and fellow colleagues discuss what might be wrong. Being scared of what might be the problem that they discussed, Okamoto takes a trip to the Hospital and for a curious reason too. When he is called to the doctors room, he is asked to take a blood test. Unsure of what this means, Okamoto jumps to conclusions, thinking he is going to die. However, he is gravely mistaken and his curiosity will soon establish into an entire different feeling that will want to give more blood.

Arihisa Aokura needs money. He needs money in order to support his family of orphans and earn a living at the same time. Looking online for potential employers, he finds a posting for a part time job in an "evil organization." Seeing that the pay and benefits were fairly substantial, he took the chance and took the interview. He was somehow hired and now has to work as a henchman inside the evil organization "Antares." Will he be able to survive the onslaught of missions against heroes while providing for his orphan brothers and sisters?

Little bit special and inexperienced—
Kids grow up as they meet and fight each other.
The beginning of Park Hwi Jung's new School Life/Fantasy story.

Kyuutarou Horikita is the tall, dark and handsome... cleaning expert of Kurokado High. His classmates find him mysterious mostly because he's hard to get to know. One day in his club's room in the school's oldest building, he stumbles upon a sleeping maiden: transfer student Fumi Nishioka.

With nowhere else to go and having the eyes to see spiritual dirt, Fumi will learn from the cranky Kyuutaro how to rid the school of the grime that attracts spirit-damaging bugs, and how to fight the bugs themselves.

Has she finally found a place she can call home in the large house of Kyuutaro's small family of sweepers? Will her brazen goal of marrying a rich guy disgust or amuse them? And her heart, once it learns the way of purifying cleansing, will it be cleansed in return—in spite of her missing memories and her ever-looming secret?

Note: This three-volume cleaning fantasy powers up and continues in Queen's Quality!

With SATs approaching closer and closer, can she protect the love and peace in this world? A tale about Han-Yurem, who became a magical girl in her 3rd year of highschool, and the mysteries that surround her.

From MangaHelpers:

28 July 2061 was an unlucky day for Raiji, in which he was falsely accused of being a groper on public transport. That evening, he joined his friends, Yuma and Osamu, to watch Halley's Comet. The comet appeared to arrive a few hours ahead of schedule, but it didn't just pass by in the night sky. Instead, there was a blinding flash, and all the people Raiji and his friends had been watching with vanished. Not only that, but the area around them was suddenly filled with nightmarish giant mushrooms and twisted human faces. In this new, violent world, the three of them will encounter dangers human and inhuman! [tethysdust]

Blue Dragon, Red Phoenix, White Tiger, and Black Tortoise.
To stop the sacred spirits of the Heavenly Realm wreaking havoc in the world of humans, successors of the Four Deities are born in each generation to guard the barrier with the Heavenly Realm, using the powers of the four sacred spirits. And the place they gather to train before they ascend to heaven is Doonggule, a traditional tea house in a small country town.

This manga is set in the Western Xia state at the beginning of the 13th century, when there were violent, ongoing incursions by the Mongol army. Guided by Suzuki, a student who has transferred from another school, a present-day boy called Sudo, a high school student who has been plagued by a vivid dream of a battlefield, is reborn as Shutohel, a female warrior for the Western Xia army, who has lived for vengeance on the Mongols, and travels to the battlefield. At the same time, the Mongol prince Yurul defies his own army, which is trying to destroy the Western Xia script, and makes plans to protect a collection of Western Xia writings. This is an epic, long-form action manga featuring elaborate, dynamic depictions of combat and the enigma of an ancient script.
Note: Won the 16th Tezuka Osamu Cultural Prize's New Artist Prize in 2012.

Takeo, the most unfortunate girl in the universe, pulls on her usual protective gear and goes to her first day at her new school. Having decided to give her parents some relief by living on her own, she ends up, due to a per-usually unfortunate housing mix-up, moving into an inn called Hyakkisou (the Manor of 100 Demons). The life of the young Takeo—or is it Take-woe?—will begin to change the day she sees the youkai... and vice versa.

Affectionately set in an everyday modern Japan with a Hellish war lurking in the background and high-school acceptance issues in the fore, the characters, setting, art and plot all make this story well worth crossing the threshold of Hyakkisou!

From Easy Going Scans:

The Great Shang dynasty has been in power for many years, but the Gods have found fault with the new emperor. Instead of submitting to their will at the expense of his people, the emperor resolves to throw off the Gods' yoke and free humanity. However, this means not only will he face the Gods, but also a rival, the young Zhou—who submits to the Gods' will for nothing but his own purposes!

The fate of the dynasty, nay, the fate of all humanity will be determined by this great battle between the forces of Heaven and Earth!

Sia Lee is a modern vampire that absorbs the energy from touching a human's body instead of drinking the blood. Thankfully, she is a model with gorgeous looks, so she does not have any problems with having relationship with guys. However, Jiho Shin, whom Sia desperately wants to touch, has mysophobia.

After the assassination of the powerful Godfather, Don Pazolini, the world has been thrown into chaos. Many mafia try to fill the power vacuum, but there is a rumor that Don Pazolini's son is hidden away somewhere. That son is Nero, an orphan who is raised in a bar with showgirls as his friends. He dreams of one day finding his parents, but he doesn't know who they are. One day, he encounters a haunted baseball bat, who names himself "Pucchi" and refers to himself as the Pazolini family 'fantasma.' Pucchi insists that Nero come with him to become the new Godfather and rebuild the Pazolini mafia family. Nero is reluctant, but quickly realizes he has no choice, since there is a price on his head and his identity is no longer much of a secret.

Kagefumi Merry takes place before the events of Yumekui Merry, and follows the adventures of a slightly different Merry than we are familiar with.

On the planet Paradyze, a war between the surface and underworld has been going on for centuries. A young cyborg fox named Maze fights for the resistance against the underworld, but has lost hope for an end to the war...until an alien named Grumble crash lands on his planet, and brings with him the technology to change everything...

Plot revolves around high school freshman Shingo Susa as he is invited by his crush from middle school Sayuri Shiroyuki to the school's supernatural club. Over the course of the series Susa begins to gain supernatural powers, something that prodigy Rei Uryu, attempts to awaken to bring out the psychic giant, Susano Oh to destroy humanity and establish a new world order.

Won the 4th Kodansha Manga Award for Shounen in 1980.

From Aerandria Scans:

Noriko is caught up in an accident while she is going to her track and field competition. When she opens her eyes, there is the young doctor Shinoda who seems very concerned about her. She is attracted to his child-like smile, but from his lips, she learns a shocking truth - in the accident, Noriko has lost her physical body and what remains is only a brain, stuck in a little black box?!

Note: The side stories in volume 1, 2 & 3 are written in novel format.

Accompanied by a talking lantern, Mika pursues her sister on a quest to retrieve that which was stolen from her long ago.

Struggling manga author Satoru Fujinuma is beset by his fear to express himself. However, he has a supernatural talent of "noticing things" that forces him to help people.

Boku dake ga Inai Machi Gaiden