Hachiouji Tarou is an average 2nd year high school student. Since his father died, leaving him as the head of the family, he’s been constantly pulling his brother out of trouble. One night, when he came back home, his mother's head was rolling on the floor, and an evil spirit had hold of his younger brother. Instead of helping him, he hesitated and stood frozen with fear while the spirit got away with his brother. Now Tarou is on a quest to find his brother and exterminate evil spirits.

From Yen Press:

Twelve years after her loved ones were brutally murdered at the annual family meeting, Ange Ushiromiya, now eighteen, is the sole heir of the Ushiromiya family. Ostracized by her peers, Ange seeks companionship in the pages of a diary left behind by her cousin, Maria. The diary offers a precious glimpse of Maria’s world-her struggles at school, her friendship with stuffed-lion Sakutarou, and her fascination with magic. It’s as if the diary contains the last remnants of Ange’s dear cousin…and an opportunity for Ange to discover the magic within herself…

Question Arc
1. Umineko When They Cry Episode 1: Legend of the Golden Witch
2. Umineko When They Cry Episode 2: Turn of the Golden Witch
3. Umineko When They Cry Episode 3: Banquet of the Golden Witch
4. Umineko When They Cry Episode 4: Alliance of the Golden Witch

Answer Arc
5. Umineko When They Cry Episode 5: End of the Golden Witch
6. Umineko When They Cry Episode 6: Dawn of the Golden Witch
7. Umineko When They Cry Episode 7: Requiem of the Golden Witch
8. Umineko When They Cry Episode 8: Twilight of the Golden Witch

The side story arcs are:
- Umineko Biyori
- [m]Umineko no Naku Utage ni: Tea Party of the Witches[/m]
- Umineko no Naku Koro ni Episode X
- Umineko no Naku Koro ni Tsubasa
- Ougon Musoukyoku
- Umineko no Naku Koro ni Shi: Forgery of the Purple Logic

Based on the visual novel of the same name. In 1986, between October 4th and 5th, members of the Ushiromiya family gather on the secluded island of Rokkenjima to discuss the division of the family's massive fortune upon the impending death of the family's head, Kinzo. However, when a typhoon traps the eighteen people present on the island, six people are mysteriously murdered. The remaining people struggle to survive as the murders continue, supposedly by the will of the legendary Golden Witch, Beatrice.

Other manga:
+ Triage X manga
+ Sidonia no Kishi manga

The manga centers on Poro, a demon from the underworld who comes to the human world.

From MangaHelpers:
After a terrible earthquake, Satoru wakes up in a pitch black cave that him and his friends were exploring. Desperately moving through the crumbling cave with just his backpack, he expects a warm rescue once he gets out. But what awaits Satoru was an unbelievable fact: Japan has sunk underwater due to the earthquake and he is stranded on an island with no one to help him. Can Satoru learn how to survive by himself?

This is about a lazy baseball player, Taro, and a very serious baseball player, Takami, who want to make it to the top. They cross paths on a bus that crashes. Takami dies and Taro lives. Taro visits Takami's grave and sees Takami's ghost. His ghost tells Taro to "switch" with him and take him to the koshien to fulfil his dream.

Included in this manga are three unrelated short stories:

- Usagi to Kame to Strike

- Live Alive

- Cross Beat

This is the story of two young boys. A route that the Japanese bike and the other is a boy who worries quickly. But these two people have something in common. It is the gift for football. And together they will try to win the football club of the school Jakusho Sakuragi.

What's a guy to do when a militant girl demands he date her little sister? Crazy right? Well, it's exactly what happens to transfer student Kakizaki Kokera. The Harimoto Sisters have a strange love-hate relationship he just can't help but get dragged into. And what's more, there's a strange town legend about a middle schooler who cleaned up the town with overwhelming violence five years ago called Urooboe Uroboros (Half-Remembered Uroboros).

From here:

Elizabeth Whitehead is a foreign teenage girl with a terminal illness who is particularly fond of air races. When she needed a new engine for her airplanes, she goes to Japan to a famous smith, Aramaki. Aramaki has stopped making jet engines as he still hasn't forgiven himself for contributing to WWII, but upon hearing Elizabeth's situation, he offers his services.

From Seven Seas:
Sumire Takahana is a seemingly normal school girl cursed with the ability to see malevolent ghosts known as Viruses. Her life hits a crossroads after a run-in with a gothic lolita-clad monster killer for hire, Lucia Nahashia. Not content to stay on the sidelines while these Viruses prey on the weak, Sumire reluctantly decides to join forces with the mysterious, eye patch-wearing Lucia to hunt down these Viruses before they can hurt anyone else.

Based on the Vampire Savior installment, from the DarkStalkers video game series produced by CAPCOM.

In the world of makai, there are horrible monsters that humans fear, called Darkstalkers. Lillith, a fellow Darkstalker, falls to Earth (London) and befriends John. What will he do when he finds out what she is? Will Lillith survive Master Jedah's attacks??

From Boku-Tachi:
Humans are suited to be come a warrior of the Gods world. Once proven to be the holder of an honourable soul, a Goddess - The Warrior Virgin - will lead and show those the way into the Gods world, and yet dead, their souls will be given the opportunity to walk down the path of life. Necromancer, Lezard Valeth and his young apprentice Louie meet a "Hero" from a small town. Is he perhaps one of these honourable souls and what interest does Lezard have in him?

From Valkyrie Scanlations:

The princess of the kingdom of Dipan, Alicia, was abandoned by her parents when she was still a child. The rumour says that she was posessed by a Demon and therefore lost her life. But the truth reveals different. Alicia in truth, inherits the soul of the Battle Maiden Silmeria, one of the three Valkyries, what she has to hide from the rest of the world. That of course gives people reason to think she has a split personality. She is taken to a castle far away from her kingdom and hidden from the public and ever since living a quiet life. Until that one day when Odin, the lord of the gods, decides to come after the lost Valkyrie and forces her to return to Valhalla...

Jae-in is an irrepressible girl who aims to be a champion, and Tae-jin is the innocent boy who loves her.
This is the story of their challenges on the road to the championships, and an unlikely summer-time love.

In the Houkago Play Series:

V.1 -
4-koma about a high-school gamer and his bossy tsundere girlfriend.

V.2 -
About a gamer and his mangaka girlfriend.

V.3 -
About a boy and a girl who are both gamers, though they play with different styles.

V.4 - R

V.5 & 7 - High Heels

V.6 - Maniax

Vongola GP (Gran Prix) is spin-off series of Katekyo Hitman Reborn!, made by Takayama Toshinori. Manga introduces Tsunayoshi Sawada, called No-Good Tsuna who is descendant of world's legendary racer, Primo and his side-kick Gokudera Hayato. They battle on various members from the original Katekyo Hitman Reborn! plot.

Reincarnated to a werewolf magician, the Protagonist Vyett was instated as the vice head of the Demon Lord's third brigade force. Occupying a remote market town, he was entrusted to management and defense.

"As a former human, born a monster, I can understand the sentiments of both sides well enough. Because of that, those around seem to think I'm a man of wisdom, or something of the like, but it's really just one trouble after the next. I have to follow those monsters that are overly quick to resort to violence, and do something about the humans, who start to complain immediately. So today as well, I'll do my best at managing the Demon Lord's main force."

Official manga page