From Go! Comi:

Like most teenagers, Mashiro Ichijo has a secret. But Mashiro's secret is that he’s neither fully male nor female! So far, Mashiro's been able to live his life as a boy, but all this changes when he's informed of a new class he must take in order to graduate from his elite prep school. To pass, he must find the “Key”…and the only way to find it is to enter into a nightmare world where his body and soul are put at the mercy of the worst kind of enemies: his classmates!

SERIES 5: Vento Aureo
Set in 2001 Italy, the story follows Giorno Giovanna, son of DIO, and his dream to rise within the Neapolitan mafia and defeat the boss of Passione, the most powerful and influential gang, in order to become a "Gang-Star" and make the world a better place. With the aid of a capo and his men, as well as his own resolve, Giorno sets out to fulfill his goal of absolving the mafia of its corruption.

A boy wakes up in a strange room and finds a girl passed out with him. They find out they both have weird collars on. The boy has a phone which seems to be connected to the people behind this. They want them to do what?

The "mysterious school comedy" centers on the unusual members of a high-school literary club. Touko Amano, a high-school senior who calls herself the "literary girl" as the club president, is actually a supernatural creature (youkai) that devours stories — she tears pages from books to munch on them. Her club subordinate is Konoha Inoue, a second-year high-school boy who writes stories every day for Amano to eat. He once wrote an award-winning novel, but he wrote it under the penname Miu Inoue so readers thought the author was a mysterious 14-year-old bishoujo novelist. The stress from the novel's fame and its movie and television drama plans turned Inoue into an introverted recluse.

After her normal, happy life shatters, Tokiko and her father move to a small seaside town to live with her grandmother as sixth grade starts. There, the sound of the waves brings back a distant memory from when she visited seven years ago, a memory of almost drowning in the sea and being saved by a merman. Are there really mermaids in that sea? Tokiko adjusts to her new life in the small town as she holds out hope of once more meeting the merman who saved her.

The story centers around the film crew for Idol Survival, the internationally popular television program where swimsuited idols compete in games. The crew arrives on the same isolated South American island that TerraSave member Claire Redfield is visiting on an investigation.

Saitou Shinji is an Ordinary High-School Student living a peaceful life on a peaceful island… way too peaceful for his tastes. The only two things he enjoys on the island are the pranks he plays and the time spent with his Childhood Friend Kana, a cheerful girl who loves taking photos and understands Shinji better than anyone.

However, when he runs away after an incident where he got angry and punched several classmates in the face, he receives a mysterious e-mail on his cellphone: "If you answer this e-mail, you too can become an invisible man!" He answers it while laughing it off… but the day after, everyone has inexplicably forgotten about the incident, and a mysterious white-haired girl appears before Shinji, calling herself an "invisible woman." He soon realizes that answering this e-mail may take away from him the only thing he holds dear…