A small group of adults have been invited to a reunion at their old high school to remember the loss of their classmate Kiriko, after receiving a letter "From K."

Not knowing who "K" is, Ryosuke, a young man with short black hair that used to know Kiriko, has to uncover the truth of Kiriko's mysterious death. As he slowly regains his memories and his fellow classmates start suddenly dying around him in the most horrific manner, he realises that it's far too late to say sorry.

Our unlucky protagonist, Jin, uses the trunk of a sacred tree to carve a statue for a school project. When he takes it outside, to his surprise it begins absorbing the surrounding earth and transforms into...a girl! So naturally this guardian deity is pretty pissed that her tree was cut down, and lives with Jin while she takes out her anger by squashing bugs...er, cleaning the "Impurities".

Tomboyish Himeko loves sports and playing with the boys, but longs to be a feminine, gentle girl like her name implies. When it looks like all is lost, suddenly a familiar face gives her a magical hair ribbon that grants Himeko the ability to appear like anyone in the human world in return for being a magical observation subject.

This is a remake of the classic shoujo manga and anime of the early 90's by Mizusawa Megumi.

From Entropy:

This is a set of one-shot stories of working people drawn from the viewpoint of Matsukata Hiroko, who is a 28-year-old single woman and is an editor of Weekly Magazine, JIDAI. She’s often at odds with Tanaka Kunio, a novice editor. Her work already stresses her out and he’s unapologetic about his own mistakes! Everyone refers to Hiroko as a masculine woman for how seriously she takes her work. She smokes too much, works too much, and never has sex. However, when it’s time to get a story done, she switches into “Working Man” mode where her testosterone in her blood increases, she works three times her normal speed, and all thoughts of life’s necessities disappear.

Hapi Buni is a dark comic about an optimistic bunny with terrible luck. Always positive, Buni doesn’t understand that the cute world he lives in is usually out to get him. Hapi Buni includes exclusive Buni comics not found anywhere else online. Started on bunicomic.com in 2010, Buni was named Best Online Comic by the National Cartoonists Society in 2014.

From MangaHelpers:

28 July 2061 was an unlucky day for Raiji, in which he was falsely accused of being a groper on public transport. That evening, he joined his friends, Yuma and Osamu, to watch Halley's Comet. The comet appeared to arrive a few hours ahead of schedule, but it didn't just pass by in the night sky. Instead, there was a blinding flash, and all the people Raiji and his friends had been watching with vanished. Not only that, but the area around them was suddenly filled with nightmarish giant mushrooms and twisted human faces. In this new, violent world, the three of them will encounter dangers human and inhuman! [tethysdust]

After their parents are killed in a plane crash, Ryuuichi and his younger brother Kotarou are taken in by the chairman, who they never met before, of an elite academy. Ryuuichi becomes the school daycare's new babysitter.

Blue Dragon, Red Phoenix, White Tiger, and Black Tortoise.
To stop the sacred spirits of the Heavenly Realm wreaking havoc in the world of humans, successors of the Four Deities are born in each generation to guard the barrier with the Heavenly Realm, using the powers of the four sacred spirits. And the place they gather to train before they ascend to heaven is Doonggule, a traditional tea house in a small country town.

From Easy Going Scans:

Chang An in the Tang Dynasty of China (618-907): The demon star is passing through the sky, calamity is about to befall the Tang Dynasty - because of a woman.
Skilled in martial arts and war tactics, Princess Li Chang Ge sets out to avenge her family and take back the throne.

A spin-off manga includes various comedy gags of characters in the main series.

Average Adventures of an Average Girl is a webcomic that talks about bad luck, a little bit of daydreaming and a lot of personal (and weird) daily experiences seen from the eyes of young wanna-be artist! If something can go wrong, it will go wrong. But it will make a great story!!

Collection of oneshots:

1) Compass of the Heart
Miyahara Yoshimi is troubled by the gaudily dressed host who always comes into the convenience store where he works. But when Tsumagi Makoto passes out in front of the store, they become friends.

2) The Difficult Couple
Continuation of chapter 1.

3) Singing Stray Cat
Prequel to chapter 1.

4) From Rain
Accidental death, murder, guilt and punishment affect a man, his younger cousin and the cousin's best friend.

5) Summertime
When Haruhiko's summer plans with his girlfriend fall through, he ends up shuffled off to visit his cousin near the beach. But cute waiter Nanami looks so shocked to see him, have they met before?

6) As Long As There's Love, Age Doesn't Matter
Tomo wants a little affection from his cold older lover Reiji, and he's not speaking to him till he gets it. After two weeks, is it all over for Tomo and Reiji?

Takeo, the most unfortunate girl in the universe, pulls on her usual protective gear and goes to her first day at her new school. Having decided to give her parents some relief by living on her own, she ends up, due to a per-usually unfortunate housing mix-up, moving into an inn called Hyakkisou (the Manor of 100 Demons). The life of the young Takeo—or is it Take-woe?—will begin to change the day she sees the youkai... and vice versa.

Affectionately set in an everyday modern Japan with a Hellish war lurking in the background and high-school acceptance issues in the fore, the characters, setting, art and plot all make this story well worth crossing the threshold of Hyakkisou!

Nike, the fourth princess of the Rain Dukedom and one who holds the power to call forth the rain, travels to the Sun Kingdom to marry King Livius on behalf of her country after losing a game of rock, paper, scissors to her three older sisters. Upon arriving at the Sun Kingdom, she discovers that the Livius, who conquered the world in only three years after his ascendance to the throne, is only eleven years old!

"It's a blessing that there is a person who listens to my story."
Not an ordinary, but an ordinary romance comic.

This webtoon focuses on Suwan, an ordinary high school girl that just cut ties with her two best friends. While feeling sad and alone under her frequent spot, the Tunnel of Tears, she befriends a blonde costumed gentleman (in a bunny suit) who listens to her troubles and comforts her. She also makes friends with a gal named Miel and her group, while continually doing what she can to comfort and help her friends just the same.

Having lost his money, lover, and future, a man who has given up on everything finds himself reincarnated in the kingdom of Altodestenia. He, Lectival, has no memories prior to being saved by Meriela, the daughter of an aristocrat, and now finds himself rising up to save the kingdom in its current crisis.

Ken has never been good with words. However, he learned to overcome his shyness when his classmate Takumasa approached him with an exchange diary. In high school, problems start to arise in Ken's and Takumasa's relationship as they face their feelings, future paths and possible separation.

*There is an extra about another couple that is still untranslated.

Fifteen years ago, natality decreased greatly in Japan and the few who were born during that time are called the "Old Generation" or "Oldgens."
Hanasaka Haru, a 15-year-old Oldgen, has never met any classmates before. Now, he goes to school for the first time and meets Himeshiro Sakurako. But Sakurako is not quite the ideal classmate he imagined, and his dream school life isn't turning out the way he wanted it to...

In Tokyo, an unchanging despair is lurking.
Mysterious man-eating beings, ghouls, run rampant in Tokyo. Living hidden during everyday life, the existence of ghouls, whose true identities are shrouded in mystery, permanently terrorizes Tokyo's residents.
At CCG, the sole institution that investigates and resolves cases related to ghouls, Haise Sasaki has been assigned a certain mission. While dealing with the unruly four problem children known as "Quinx", has Haise's days of suffering begun?

With the space program attempting to travel to Mars, 21st century scientists were tasked with warming up the planet so that humans could survive on its surface. They came up with an efficient and cost effective plan of sending cockroaches and mold to the surface so that the mold would absorb the sunlight and the insect corpses would serve as a food source for the mold.
It is now the year 2577 and the first manned ship to Mars has landed on the planet and the six crew members are ready for their mission. But what they find are giant mutated humanoid cockroaches with incredible physical strength. The crew members are easily wiped out, but not before sending a transmission back to Earth. Now, humanity will send elite warriors to exterminate the mutated bugs and claim back Mars.

Note: Was nominated for the 6th Manga Taishou in 2013.