A short story about a newly hired maid who pretends to be a girl to get the job and his young miss.

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.

what happens when gamers are summoned back to the real world in their game avatars

From 200 wpm:

Once upon a time, there was a mermaid: "I want to become human so I can fall in love" she said. When her wish was granted, the lower half of her body turned to foam and she became a human... MALE ♂!?

This is the love story of a 30-year-old virgin man and a beautiful (male?) mermaid!

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From LuffyNoTomo:

A 30 year old man named Koganei, Manato is down on his luck. He can't seem to get a job, has little money, is still a virgin and is giving up on his dream. Sitting alone on a swan boat in a pond next to a shrine, he holds a lottery ticket thinking this is the only way his dream may come true. But the wind blows it away and he falls into the pond, thereupon seeing a beautiful mermaid!

Manato ends up going back to the pond and after the mermaid decided not to kill him since he gave her food, she tells him about her dream to become human and how she wants to find love (she collects coins and throws them to a shrine in order for her wish to come true). Manato decides he doesn't want to get involved anymore because he has his own worries, but after another bad day he goes back to the pond. She finds him again and after listening to his complaints, she decides to give him all her saved up coins in order for his wish to come true. She suddenly turns into bubbles and disappears.

Confused and upset, Manato hears a strange voice and a god from the shrine comes to say that she will take the coins and grant him a wish. He decides to use his wish to bring back the mermaid as a human. His wish comes true and he sees the mermaid back as a human, but she's a guy! What will happen in this crazy love comedy!?

From Which Scanlations:

One day, Kengo Yagami found some of his classmates teasing a turtle that lived behind their school--and he beat them up. But when the turtle spoke, he was so shocked that he kicked it as hard as he could. Unfortunately, the turtle was actually a god, and as punishment, he switched Kengo's body with his childhood friend Mitsuka's, and their new bodies are causing both of them a lot of trouble at school...

Also includes the one-shots "Kirakira Hoshi no Ana" and "Kimi wa boku no Saboten."

Three girls want to make a girls-only band, but they need a singer. This one cute voice turns out to be from a boy! What will happen when this boy gets involved with them?

When other people experience a body transformation, it is inevitably either male to female or female to male.

Me? I wake up to find myself transformed into two different bodies.

Both a male body and a female body, one conscience operating two bodies, all sorts of embarrassing moments.

Walking together normally makes other people think that I am sweethearts with my other-self, such sadness.

Also, the entire business of a hero rescuing the beautiful maiden, I call Bull.

I get slashed by a sword and my female body gets abducted, and he wants me to thank him?!?! Can it be less of a tragedy?

"It feels TERRIBLE to have a brother!"- we both thought.
Until one day, we both made a wish to turn the other into a sister..

Once rich, now poor. Two souls, one body. How did she come back from the dead? Just what happened to her in the haunted house?

Alice Academy is a famous school exclusive for children with an Alice, children with special powers. It's affiliate music school, the Alice Academy Opera Troupe, now opens up to regular students as well.

Andou Hikari's brother has an Alice and is a student of the Alice Academy. She decides to enroll to the school. There she is paired up with Shinomiya Ema, a student with a secret...

It's a story about when you wake up, your gender changes.

A boy who used to be abusive to girls wakes up one day as one.

“I'll go back being a boy soon,” he thought, however that was not the case. Follow Akira as he grows and learns little by little to accept the puzzling changing in her surroundings and her heart.

This is the story of a village where a deity is--on the day of the village festival, the deity endows a boy, Mao, with a destiny. That destiny is to live as a girl. In a small village where forests, lakes, fields, fish, insects, and flowers flourish, Mao, his sister, and his friend confront fate.

Kazuki Yasaka, an 8th grader living in Asakusa, is turned into a Kappa along with his classmates Toi and Enta by a mysterious creature named Keppi, after they break inadvertently a statue of a Kappa, the guardian god of the city.

They are then ordered by Keppi, who claims to be the first heir to the throne of Kappa Kingdom, to fight against the Kappa zombies, bio arms created by his enemies, if they want to return to their human form. In order to kill them, they have to make a specific sound called “Sarazanmai” which is produced only when the three of them are united, but the three boys cannot connect at first.

In addition, one of their secrets is revealed to each other every time they emit the sound!

They finally accept to take risks collecting the “Plates of Hope,” given by Keppi when they defeat the Kappa zombies, and which can make their wishes come true. However, some trouble occurs over the plates...! Along the course of the fights against the Kappa zombies, their fierce past and inner conflicts keep getting revealed. This is the sarcastic fantasy of three boys who don't feel connected to their important ones, getting to realize the real meaning of bonds.

This is a story about high school boys who seem to have become magical girls.

A "trouble comedy" about a fujoshi girl who meets a yuri otaku boy.

From Antisense Scanslations:
Set sail in this shipboard drama set in the Age of Exploration from amazing mangaka Nagano Mei. The time is the Industrial Revolution, the location England. Monica, a young girl living in the slums, was making a good living as the nursemaid of Evan, a young child of a wealthy household. But when her master's ship goes missing, she's cut loose. A year later, while visiting his coffin, she happens to see Evan, the child she once took care of. She decides to abduct him and take him away with her on a ship.

Disguised as a man, Lu Dingning picks up a bunch of girls, with her gentleman index on max and her prince charming smile leveled up! Women are constantly surrounding her and men are getting mercilessly bent in her presence.
Life motto: As long as the hoe is dancing well, there's not a single boyfriend she can't steal!
Zong Jize, king of the city, treats her as his brother but ends up pushing her onto the bed.
Lu Yining says furiously, “Master Zong, I treated you as my brother but instead you sick bastard just wanted to sleep with me!”