The title story, “The Mermaid Prince,” told in three chapters, is a coming-of-age story set in Okinawa. The boy, Mugi, has a fascination with mermaids. He moved in from Tokyo when his sister got married to a local man, and doesn’t quite fit in. On the day he met the girl, Madori, she was just coming to terms with her new family situation. His thoughtful gesture made her view him as her Prince Charming.

In the second story, “Snowy Day,” a homeless father and son take refuge from the snow in a library. The librarian soon finds out there is more to them than meets the eye.

The third story, “Ametsukigahara,” is a two-parter about a girl named Akari. There’s not much she cares about in this world, except maybe her friendship with Fumika, who’s afraid of boys. But then Fumika gets a boyfriend, and something happens that makes Akari even more jaded than she already was.

[From AtoZ Manga Translations]:

As a child Jinae made a wish for her and her special friend to meet again one day to look for mermaids. Now in high school, Jinae still dreams about that encounter. Could this be a fairy tale with a happy ending?

From Aerandria Scans:

The beautiful singer Lucille and his orchestra invite you to the city of fear where puppets hunt down humans. The puppets are playing an oratorio of magic and illusions!

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This manga also features the unrelated short story Camelot Garden in vol. 5.

The 200,000 KM diameter artificial celestial body of APOSIMZ. Most of its volume is its core space, which is covered by a superstructural shell. Fifty centuries ago, the people who lost a war against the core lost their right to reside legitimately in APOSIMZ, and were left behind on the extremely cold surface. They face the spreading Frame disease. And aggressive automatons which appear frequently on the ruins level. Even so, somehow people survive.

A group of high school students visit the inside of a mountain on an agricultural trip. While staying at a farmer's home, they learn the rural life. However, the village doesn't exist...? A shudder runs down everyone's spine as a lot of inexplicable events happen in the village, that now restricts entry. What are the high schoolers fate?

Set in the far-future in 28XX, this series of interconnected stories follows the relationship between humans and androids. Two twin brothers, also androids, are "puppet masters." Arashi (Storm) has the ability to animate androids or "dolls" for a specific purpose and Shizuka (Quiet) can shut them down after they have fulfilled their roles.

This is an on-the-road, rise-to-glory tale about Hojo Soun, a pioneering daimyo of the Warring States Period who became a lord overnight, and Flying Kato, the legendary ninja who supported him from the shadows. It was originally created by Koike Kazuo, one of the gods of modern manga, and is brought to life through the bewitching battle-art-style of Momojiri Saburou! Just before the chaos of the Warring States Period began, after the Muromachi Period, a young Hojo Soun, who has taken the name Ise Shinkuro, begins a journey to enter into the service of a samurai family. All he has to lead him is his confidence in his spear skills and his passion. Along the way, he finds a poor-looking child sitting in the shadow of a tree, and offers him water and food. This act ends up turning his entire world upside down....

Those who have a cat, know how naughty they can be. But what kind of cat uses this kind of ninjutsu to irritate its owner and avoid to be sold with his siblings?! Well, none other than the black cat Kuro!

10-year old Ken (Ken'ichi) Mitsoba is an average kid who goes to elementary school, and struggles with his studies. Meanwhile from ninja land aka Land of the Ninjas, a little ninja named Kanzo Hattori comes, and befriends Ken'ichi. Hattori is now a part of the mitsoba family along with his brother Shinzou, and his ninja dog, Shishi-Maru. Hattori helps Ken'ichi with his problems, and constantly keeps an eye on him, as a good friend.

Nobu, a 32 year old salary man, is spreading justice from the shadows as a ninja while maintaining his family and working at his company. What he doesn't know is that he is being followed by mysterious persons and his gifted family. Can he put everything in order?

In the 15th year of the Tenmon era, Fuuma Kotarou—the fifth in a long line of fierce warriors—fought for survival in a world torn apart by endless warfare and haunted by dark, supernatural forces.

Driven by a single, unyielding resolve—to do whatever it took to stay alive—he cut down countless foes, narrowly escaping death time and again. Yet fate had its own plans: captured and executed, his life seemed to come to a tragic end.

But just when all hope was lost, a mysterious figure known only as “THE SEER OF WORLDS” reached out to him. In that fateful moment, the cycle of reincarnation was unleashed, and Fuuma Kotarou was reborn in a completely new realm—a second chance to reclaim the humanity he once lost.

A slice-of-life series about a girl named Shinobu, who is perfectly normal and not a ninja whatsoever.

From Kodansha Comics:
In the gritty, futuristic city of Neo-Saitama, the streets run slick with acid rain and blood. Here, an army of cybernetics-clad ninjas runs amok under the menacing rule of the Soukai Syndicate. As incessant strife wrought by a ninja turf war takes the lives of all citizens who end up in the crossfire, one can only hope to end the day without getting a suriken to the skull. But in these dark, tragic times, a spirit of vengeance rises to kill all wicked Ninja who terrorize Neo-Saitama. This crimson avenger is Ninja Slayer, and he will not rest until all Ninja have been slaughtered at his hands.

From MangaHelpers:
Mikado Shuuji is just an ordinary guy, but he has a very unusual knife that he uses for cooking. It's actually a famous short sword that marks its owner as the head of the ninjas, and now there are hot ninja girls coming after him to take it back. Hinamori Botan is one of those hot ninja girls, but her efforts to attack Shuuji mostly end up inadvertently stripping her. After she concludes that she does not want to steal the sword and kill Shuuji, she ends up deciding to serve him as a ninja instead. Now she must protect him from the other ninja that come to claim his sword and his life.

The story in Ninku is about an odd-looking 12-year-old boy named Fuusuke who is a powerful warrior from the Ninku school of martial arts, a style that mixes ninjutsu and karate.

It is explained that before the present time in the story that those who could use Ninku were targeted by an evil empire and the Ninku corps were formed to combat the menace. The names of the corps were taken from the twelve Chinese zodiac animals and each captain of the corps was called the zodiac animal Ninku master. When the war was over, the Ninku were defeated and almost all of them were killed (except for a few corps' captains) since they were useless and were also dangerous for the rulers. At the beginning of the story, three years later, Fuusuke, the young former captain of the 1st Ninku corps and controller of the wind and Hiroyuki, his flatulent penguin, start searching for the other Ninku captains, each of whom can control various elements. However, a new group of Ninku users has arisen and are trying to take over the world. Fuusuke and his penguin must defeat the new Ninku empire with the help of his old comrades.

Source: Wikipedia

After being awarded the Nobel Prize, child prodigy Alice T.P. Riida runs away from home and creates the first Artificial Human, Ninomae Shii. Along with Shiratori Jun and Kurosaki Yaoki, Shii now struggles to find out for what reason he was made for.

From Icarus Bride Scanlation:

This story is about a university student named Mikari who finds herself falling in love with the most unlikely of partners: Kaga-san, a 52 year old widower who lives in her apartment building. The scent of the incense sticks he burns in his deceased wife's honor clings to his body, drawing her in.

Apart from the fact he’s in the student council and has quite strange tastes, Shima is an average, low-profile, quiet high schooler. Therefore, he doesn't understand why Ryuunosuke, a sports student, always glares at him every time they cross paths. Shima doesn't want to draw the punk’s attention, but the instinctive hostility of Ryuunosuke towards him troubles him, and he wants to know why the other boy hates him…

A university professor who specializes in figuring out the mentality of crime suspects is asked to help solve cases. He also has a relationship with his assistant.

This is the story of Nirugame-chan, who somehow ends up getting into trouble with her butt and going round in circles.