Boichi's take on One Piece between chapters 51 and 52 with a fight between Zoro and Mihawk. The one-shot was created in celebration of the series' 22nd anniversary.

From Aerandria Scans:

The world is said to exist with yang, the world of humans and yin, the world of mythical beasts in conflict with each other. A long time ago, two clans who were involved in an unending war exchanged an inviolable pledge and started living in their own worlds. At that time, the king who ruled over all the mythical beasts gave his own sword to the human queen whom he dearly loved and vowed that if the queen or her descendants ever fall into danger, he himself and his descendants will surely come to save them...
And now, when the third war is about to begin, a beautiful swordsman with the blood of the king of beasts had a fateful encounter with the aloof king of mythical beasts, and the story begins!

The spinoff manga follows the character Happy as he is separated from Natsu and finds himself in a world populated by animals.

Yui, Minami and Saeka are new found friends. On their way to class, a life changing event took place and has transformed them from ordinary school pinafore girls into “Pinafore Schoolgirls” superheroine.

Chika Ono spent most of her life in the city, but due to her mother being sent overseas for work, she goes to live in the countryside with her father for a year. After finally returning to the place she sent the first few years of her life, she soon realizes she can see the spirits and mystical creatures of the forest. The memories of when she lived in the forest are still hazy, but the creatures of the forest still remember her. Will Chika be able to uncover the secrets of the forest and her forgotten memories?

Tsukumogami Karuta is a Karuta card that was attached with the divine spirits of Tsukumogami. It has been passed down in the Kawazuya, a spirit medium family, for generations. However, by the Meiji period, the family had lost 41 of 49 cards. That is until they were found in the Kawazuya vault 100 years later by the 6th generation, Shiro Kawazuya! To collect the scattered 99 gods of Karuta, Shiro is wandering around Nara city together with Miyabi, the rich girl whose sixth sense just got awaken!

Multiple years ago a man in a turtleneck appeared from a different world with his cheat abilities and high intellect he cooperated with the dwarves to make the device that changed the world the “Smartphone”, years later, the world was taken by the magic of social media, and encouraged by his companions, the holy knight “folg” has decided to make an account, but with the internet filled with trolls, how will it go with the noob holy knight.

"Can you be your natural self, if you know the truth?"
"Can you assimilate into our school?"
"Can you pledge secrecy when you are a human being?"

Fukuta Neko somehow finds herself applying to and enrolling in a secret school created by and specifically for animal/human shapeshifters, though only after difficult tribulations with those who manage the school. Neko befriends a fellow classmate, the cute Suzuhara Miiko, prior to the tough task of enrolling, and afterwards discovers her new found friend's "feline" side, though this changes nothing in regards to the close relationship just started between them. Join Neko on her journey into the mysteries of the prosperous Moritaka school for the sons and daughters of this literal Noah's ark.

Years have passed after Yugi's adventures and now it's Judai "Jaden" Yuki's turn.

Judai "Jaden" Yuki is a new student in the school Duel Academy, a school dedicated to teach duelist the basics and advanced techniques.

Judai is determined to be world's #1 duelist, accepting challenges from his rivals (and friends).

Although the manga is based on the anime, the story is really different and unrelated.

Manga adaptation of the novel "Yami no Moribito", which is the second novel in the Moribito series after "Seirei no Moribito". All the Moribito novels have standalone plots.

After the events of Seirei no Moribito, Balsa returns to her birthplace in Kanbal to revisit her past with Jiguro, the man who raised her. When she finds out that he has been implicated for the death of the king, she fights to clear his name, and on the way uncovers the hidden part of Kanbal.

Sakata Gintoki is a samurai living in an era when samurai are no longer needed.
To add to his troubles, oppressive aliens have moved in to invade. Gintoki lives with Kagura and Shinpachi, taking on odd jobs to make the world a better place... and to pay their rent.

Volume 24 contains Bankara (ばんから)
Volume 38 contains 13 (サーティーン)

Tsukasa is an ordinary guy who lives an ordinary life till he meets Chikako and his new best friend Akatsuki together they are discovering a whole new world and Tsukasa's past.

From Kawaii Corner:

The strangers clad in black clothes in the organization "Death Edge". Their goal is to murder "Angels". They've killed enough people to fill the park, for the sake of thrill and adrenaline; These dark fallen Angels have landed on Earth.

A child was naturally born unable to practice asceticism/ inner strength. To get his fathers attention, he chose to practice outer strength the painful way. Spring passed Autumn came, time flew, this child grew as the year passed... He became a teenager, the thing that changes his fate is a mysterious meteoric crystal stone that's is made from a shooting star...

Food is the most important thing to everyone-- the gods in the Heavens like delicious food too. However, in the Heavenly Realm, delicacies can be eaten, but it can also be used in fights! Pheonix Siew Mai, Exploding Lava Bi Fang, Crystal Prawn Shrimp noodles... Your imagination is the limit to what you can eat. Watch how San Chi steps into the cultivation path to become a Food God. Using food to depict a brand new world of martial art and causing foodies far and near to be consumed into the world of food.

Sunny has a peculiar ability: wherever he is, there’s always clear skies and sunshine. One day on his travels he comes across the girl Raine, whose ability is the exact opposite of his. This is the whimsical tale of Sunny, Raine, and their feline companion Polkadot as they journey to find the floating island Final Rest and return home a special little sapling. And maybe, along the way, a place where they belong.

Ye Chenben is a young lord, because of a conspiracy, parents were killed, twin sisters were imprisoned; On the occasion of his death, the blood of benevolence awakened the ancient god beast and got the stunt of the god. Who is to destroy the door of the leaf house? Why is the beast and my present? And look down the young Yechen, how to change life against the heavens, the mountains and sea-sealed God!

In order to find the treasure which will recover her memory, a girl sets out on an adventure.

Series was discontinued in 2014 after Nanaki started working on her new weekly series, the popular Helck.

What would you do if one day, a time-traveling, hammer-wielding girl from the future suddenly appeared in your backyard searching for a mysterious object? Well, that’s exactly what happens to Takayuki, who is a normal high school student. Join him on a crazy but sweet adventure that delves into the world of time travel and future beings as he discovers the true power the future beholds.

Watch out malevolent fugitive souls, Higuma will send you straight back from where you came!