His name is Terawaki Kyou, a mercenary. Originally from the National Guard, he traveled across the world, hopping around different mercenary squads, until one day he finally screwed up. He was caught in the explosion of a suicidal enemy. And when he woke up...
He was in the body of a girl.

Reesha was once a prince of a powerful dynasty, but after the end of a war, his home is no more. In the the first three years of Reesha's new life, he went to school with some of his family's former subjects, now his friends. However, after they graduated, they all joined the military. Reesha's small size, due to his artificial heart, has prevented his acceptance into the military for three years running. Now, 19-year-old Reesha is living as an ordinary plumber in a town of hot springs. In order to help Reesha get around the size requirement, he and his military friends sneak into a bathhouse to appeal to the general directly. Unfortunately, this plan results in a series of unexpected, violent events which cause Reesha to finally depart his everyday life and head off to chase his destiny!
(Source: MangaHelpers)

One night an android which looked like a cat (a Necossass: Six type) suddenly appears in Katsuhiko Katsu's room. The android said she comes from the 22th century and that Katsu has left a note in a time capsule that he wanted to live with a robot-cat.

"13 years ago, an unknown object appeared at Shinjuku. That creature regularly gives birth to a demon. Therefore, our world is being eaten clean."
The military found a weapon capable of fighting these creatures, a special power known as "exex" that becomes part of the human body.
From the author of Ubel Blatt.

Rumors stir throughout the land: when the wielder of the black sword draws his dark blade, all who stand in its path are torn asunder…! Köinzell, the mysterious young boy who carries the black sword, undeniably wields it with exceptional skill, but can he truly be responsible for the bloody rumors? Pursued by the Traitorous Lances, four powerful warriors who were thought to have been defeated by the Seven Heroes, the strength of the young swordsman will be tested to its limit. At battle’s end, only the shocking truth of Köinzell’s quest will stand above the corpses of his enemies…

An epic fantasy on the grandest of scales!

(Source: Yen Press)

心剑机装
心剣機装ムサシデュアル
Shinken Kiso Musashi Dual

In the not so distant future, Earth is invaded by aliens. The United Nations instates a draft, and all humans on Earth are eligible to become soldiers. Kurando Nieno is a rather scrawny high school student, scoring the lowest scores possible on the preliminary draft physical. During an air raid from the aforementioned aliens, a rather irritable black haired girl crash lands in front of Nieno and attempts to drink his blood. The United Nations air force and Eliza the vampire have selected Nieno as Eliza's delicious new food source!

After his mother's death, Miwatari Yuu returns from Tokyo to live with relatives in the city of his birth, Ousuku. Yuu is the latest of a line of Shinto priests that stretches back generations. After his arrival, he runs into a strange girl who seems to be searching for the Northern Lights. Yuu saw the Aurora as a child, though no one believed him, and his mother had told him it was the armor of the Valkyries traced across the sky. Yuu's destiny is interwoven with this mysterious girl and the aurora, and he will not be able to help being drawn into a battle that involves both gods and humans!
(Source: MangaHelpers)

From Operation Boredom:

“'I’ll create a witch!!”

During the 17th century, the German alchemist Johann Schultz successfully created a witch. He then injected that power into his own blood.

In the present day, as a result of a scheme created by his cousin, Yomoda Rena, Shurutsu Kenichi, a high school student and a third generation German, fights on secretly as a blood relative of "Brocken", all in order to hunt down those who abuse the artificial witch theorem. Yet for reasons unknown, he transforms into a Magical Girl "Heroine"...?

“'I’ll create a witch!!”
During the 17th century, the German alchemist Johann Schultz successfully created a witch. He then injected that power into his own blood.
In the present day, as a result of a scheme created by his cousin, Yomoda Rena, Shurutsu Kenichi, a high school student and a third generation German, fights on secretly as a blood relative of "Brocken", all in order to hunt down those who abuse the artificial witch theorem. Yet for reasons unknown, he transforms into a Magical Girl "Heroine"...?
( from Operation Boredom)
Serialisation information can be found under More Info.