Junior high school student Misaki Nanao realizes the people of the town she lives in are slowly going insane. At the same time, she starts seeing Beherin, a mysterious demon. “If you make me believe you, I shall help you”. Misaki believes the demon’s words and talks about her terrifying personal experiences; however she gets dragged into people’s increasing insanity, horrific incidents and a huge conspiracy.

A high school student who likes Social Games, Naruse Hiroki was suddenly kidnapped with his childhood friend, Nagakawa Yoshika. When he wakes up, there is a realistic Rhythm Game where three high school girls dance according to his best friend Shinji's game. However, if he makes a mistake in the game, it will be a real-life version of the "Smartphone Game" that will die soon. Naruse, who had no choice because Yoshika was held hostage, was forced to participate ... Social Game x Death Game begins!

A new Tomie story, originally included with the Kanzenhan release of the Junji Ito Collection.

Based on the Shin Megami Tensei If videogame.
The setting is Karukozaka High School, which is mysteriously sucked into a void and emerges in the realm of Makai, a world of demons. Most of its students and school employees are trapped in the other world along with it.

From Dark Horse:
Misaki Saiki, a young woman with a troubled past, is a professional dominatrix in one of Tokyo's most exclusive S&M clubs. However, her real money is something she likes even less than being a dominatrix. Ever since childhood, Misaki has had the ability to see and communicate with ghosts, and that talent is put to use by the Livelihood Protection Agency, who pairs Misaki with Souichiro Kadotake, a martial artist who happens to be deathly afraid of ghosts. Using her gifts, Misaki is able to help troubled departed spirits resolve what is troubling them and allow them to move on to the afterlife. If all THAT isn't odd enough, Misaki is an albino and a virgin.

A girl with a gas mask attempting to fight back against the strange world

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!

--

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

A collection of stories inspired by Grimms’ Fairy Tales.

Story 1, G's Diary: A girl with no memory of who she is spends her days working in a house she has no memory of entering.
Story 2, Frau Trude
Story 3, The Summer and Winter Garden
Story 4, Little Red Riding Hood
Story 5, The Frog King or Iron Heinrich
Story 6, Little Brier-Rose
Story 7, The Bremen Town Musicians
Story 8, Rapunzel.

From MangaHelpers:
High-schooler Matsuzaka Satou has a reputation for being easy, but one day her lifestyle of sleeping with one boy after another comes to an end. It happens when she meets the child Shio, for whom she is convinced she feels true love for the first time. Satou may seem sweet and innocent, but there is nothing she won't do to protect their life together, including committing murder. But from where did she acquire the little girl, and how long can their "Happy Sugar Life" together last?

Included one-shot:
Volume 2: White Sugar Garden, Black Salt Cage (pilot)

Short story:
A short story was released in Young Gangan 23/24 of 2016 which is referred to below as 19.5. It was later released in Volume 6 as an extra.

A collection of 4 short stories with horror/disturbing/suspense theme

1) Shoujo Pandora
2) Beauty
3) Fish-man/Merman
4) Puppet

Count D has opened his petshop again, this time in Tokyo's Shinjuku!

For those who haven't read Petshop of Horrors, Count D's Petshop is a place where one can find animals from the most ordinary housepets to savage predators to mystical beasts that should belong only in legends. Customers often find that their new pets change their lives more than they expect, fulfilling their dreams, or realizing their nightmares.

Seven college students are coming back from their graduations. During the travel they are shocked to see a strange, cow-like creature with a human face. This accident means they only have seven days left to live. What will they do to stay alive until the fated day?

A spin-off comic based on the movie Sadako has appeared! Sadako, who doesn’t get to appear much in the film, was actually doing this and that?! Witness a short comedy from Sadako’s perspective! You may see a side of Sadako you’ve never seen before… ?

Five days after the sudden appearance of zombies... The protagonist, Masaru, who is having it rough surviving at school, is splendidly saved from this predicament by high schoolers Sekigahara Miki and Nakiri Karin. Though Masaru is at first relieved, he ends up realizing their true intentions...!!

A slit-mouth woman encounters a young boy she's unable to scare.

The protagonist is a girl with the ability to visit a surreal alternate dimension full of monsters in her dreams. One day, she encounters another human girl there and receives a plea for help.

While humans toil at their ordinary, boring lives, a battle secretly begins among a new species that evolved from humans. They disguise themselves as human children, and instead of maturing into adults, they are each gifted with a different "special power". They are the new humans, known as "Kodomo." Hinagata Heiji is a Kodomo who can bring any inanimate object to life by dripping his blood on it. In order to find his own feeding ground, he keeps transferring to new elementary schools.

Even if he forgets, I will remember

It centers on a girl named Wakaba Himekawa, who is aware that she is growing up slower than other people, but otherwise lives a peaceful life. On the same day that she finally gets her first period, her childhood friend Takaya confesses that he loves her. While Wakaba had never felt that way for her friend before, she is still happy, if confused. As she is about to answer Takaya's confession, an alarm suddenly sounds, and a broadcast begins that will change her everyday life.

Denzel Westwood is a young, talented magician without a care in the world, until one day his eyes suddenly begin to turn amber, prompting a series of events which will lead him to discover the truth of the world in which he lives and the mysterious Abyss which surrounds it. This is the story of a boy filled with light.

English version
Original webtoon