Officer Shibata Taketora works in a local koban (a small police office). He may have a child-like face on the outside, but he's more serious than anyone in his pursuit of justice! With his goal being to become a detective, Taketora confronts everyday problems that happen within the town! Various incidents within the street make him chase after and apprehend criminals!

From DrCoke at MangaHelpers:

Six years ago, Tsukihiko was caught in an assassination attempt on a little girl, Sami, when he attempted to be her shield. This incident nearly killed him and the girl together, but the little girl was the daughter of an extremely powerful family. With its vast amount of resources, the family was able to keep both Tsukihiko and Sami alive by recreating both of their bodies with cyborg technology. This has forced Sami to permanently rely on wired connection to her life sustaining computer. On the other hand, Tsukihiko has become a cyborg "Knight," sworn to protect Sami from harms way.

When he first logs-on, he sees his friend fall into a coma before his very eyes. Now Kite is searching for the answers as to why, and how to save him, inside 'The World'. Based on the original PS2 .hack series, Infection Expansion (Vol.1), Malignant Mutation (Vol.2), Erosion Pollution (Vol.3), Absolute Encirclement (Vol.4).

When an object is cherished for 99 years a deity is born within that object; also known as a Tsukumo deity. Yukiji's companion, Tamakichi, is a deity; he was born from a certain item her mother left behind. As Yukiji enters Mizuhozaka Girls’ Academy Tamakichi constantly puts in a troublesome appearance. Yukiji's hopes for a good school life looks dimmer and dimmer.

Eliza's grandmother constantly destroys any approaching suitor before Eliza gets the chance to talk to any of them. Will this be her chance when she's alone and finds a cute boy in the forest with his pet... worm?

1. Kohrogi
Mitsurugi Kai is a wizard that must pass a test of character. He doubts himself due to his past. His test is to retrieve paper charms by himself. On his way, he meets Kohrogi Orine who is a fledgling singer who also doubts herself.

2. NOIZ
Hayami Shrou can see into the future of people by touching them. Two years ago he lost his parents in an accident, while his sister barely survived, but remains unconscious. He blames himself, thinking that if he had touched them and saw into their future back then, he could have saved them.

3. dZi:s

4. X-connection 2001

From VIZ:
In the not too distant future, mankind battles over O-Parts, relics from an ancient civilization. It takes a special kind of person to unlock the full potential of these remnants from the past, and a unique breed of humans known as O.P.T.s (or O-Parts Tacticians) become a force to be reckoned with. Unfortunately, O-Parts can be used for good or evil purposes.

Jio is a young boy with a tragic past who only trusts one thing in the world: money. Little does he suspect that he is actually a very powerful O.P.T., and inside him sleeps a demon of incredible ferocity. He meets up with a girl named Ruby, and together they decide to embark on a dangerous quest to discover as many O-Parts as they can. Will Jio help Ruby realize her dream of becoming a world famous treasure hunter? More importantly, will Ruby help Jio realize his dream of--world domination?!

From Tokyopop:

Beings who possess animal-like powers walk among humans in this alternate universe. These mysterious mutants, the +Anima, are shunned by society. Four outcasts in particular--Cooro, a boy with crow-like powers; Husky, a fish-boy; Senri, a bear +Anima; and a girl named Nana, who wields the power of the bat--search for others like themselves while trying to gain acceptance in a world cruel to anyone or anything that is different.

The main character Udagawa Gosuke has received his father's dojo, mainly because his father and older brother were made to commit hara-kiri. He wasn't really supposed to get it simply because he's a second son. But due to the way his pops and brother died, he doesn't have a whole lot of self confidence, so he practices fencing day-by-day at a nearby dojo. However, because the people at that dojo are asses, he soon tries to invent a dojo and a style for people who just enjoy it.

However what really sets this aside from most shounen is that the main male and female characters are actually married. (At age 15 no less!)

The girl Utagawa Shino is the younger sister of his senpai, and is a bit...weird, to say the least. She makes rabbit masks to help bring in a bit of money, although to say that she's obsessed with rabbits would be an understatement. She claims it's because "the rabbits will someday reach the moon." When Gosuke invents his new dojo, he decides to make a style of swordsmanship known as "Rabbit Style Fencing."

Ageha Shiraishi has been sentenced to death, suspected of murdering her four roommates. In her prison cell as she awaits her execution, she tells her warden, Kyousuke, that she is innocent and that she did not commit murder. Kyousuke does some research, but finds that she is still guilty. Upon his return, he finds his superior tied up and stripped. After setting her free, he finds out that he has been tricked, and it was Ageha in disguise.
Ageha can impersonate anyone to the finest detail, whether it be hair color, habits, or even voice. She becomes the first fugitive of the Talsis Prison and she declares that she will find the real culprit. Kyousuke now only has one clue, which is "the Ageha" (swallowtail butterfly) tattoo on Ageha's back. The chase between the characters involved begins as they move to grasp the truth!

Nagasawa Shiina is just an average 3rd year high school student until her parents' company goes bankrupt. In order to pay the bills, she sells herself into prostitution. At her first job, a mysterious masked man crashes the party... and it's someone she knows.

Akumetsu is the story of Shou, a vigilante that's out trying to straighten the corrupt Japanese Government through terrorism with his "One man, One kill" code of action.

A series of three manga tankoubon released between 1983 and 1997 that collect several one-shots written and illustrated by Akira Toriyama. The stories were originally published in various Shueisha magazines between 1978 and 1994.

Daichi Kakeru is a peaceful high school boy who likes to collect cans. One day, when drinking a melon soda, a girl suddenly kisses him. The steel can transformed into a girl who wants people to appreciate cans more. Kakeru names the aluminum-can-hating girl Melon and decides to take care of her, but every time he drinks from her melon soda can, which is necessary for her survival, they kiss.

As he learns to cohabitate with her, their fun-filled days are interrupted by a government agency responsible for the economy, who not only knows their secret, but introduces them to the Akikan (Empty Can) Elect, where steel and aluminum cans fight in order to decide who gets manufactured for the market. While Melon is eager to prove the supremacy of steel cans, her Owner, Kakeru, is strongly against participating, due to an incident in the past involving his rich childhood friend, Najimi, and guns that made him hate violence. However, there are other aluminum cans who are just as ready to battle as Melon and when those two natural enemies meet, it is kill or be killed . . .

Based on the Chinese novel Shui Hu Zhuan, this series is about the trials and tribulations of a band of outlaws during the mid Song dynasty.

It is 1112, China is in turmoil with the present Song dynasty's government and its inability to control its own provincial officials from preying on their people. However, tales of a band of outlaws punishing these abusive officers called "Taiten Gyoudou" is spreading. Their deeds are giving people hope. It begins with an encounter between Suiren, a young village girl believing in the bandits, and "Falling Star" Tai Sou, a traveling swordsman whose skill precedes him.

* Suikoden (水滸伝) is a Japanese translation for Shui Hu Zhuan.

The story is of Kitano Seiichirou, a very kind and pure-hearted young man, with a horrifying, monstrous face. People being what they are, they think he's a terrifying delinquent, and there are plenty of chance misunderstandings (coupled with Kitano's convenient inability to understand what's happening around him) that propel him into the position of "school guardian", a.k.a. head thug on campus.

Jin (female) and Konoe (male) are twins and are just starting their high school career. Jin has always been a trouble to her brother, since she’s very tough and violent, and generally doesn’t behave like a girl at all. Konoe is determined that their high school life is going to be different, and he’s going to make sure she keeps acting cute and feminine. But it isn’t easy for Jin to pretend to be something she’s not…

Luchiru is a Majin who lives beneath the surface of the earth. He was sent to the surface as a spy to gather information in order to defeat the humans who are living there. But the problem is that Majins have a different understanding about humans; they strongly believe that the Human Race is far superior to them in every sort of way, but in fact it is the other way around.

How can Luchiru survive in the Human World where he has different point of views on the strength of humans, which he strongly believes that with just a touch would make him combust and be disintegrated in an instant?!

Three travelers visit a post town, a girl and a boy who seem like twins, and one man. Their goal is to seek great power, the Amanusya. In that town, they discover an evil conspiracy involving an Amanusya...

Wagashino Azuki, training secretly deep in the mountains. She's too clumsy and air-headed to be a ninja, but somehow Azuki ends up as the bodyguard of the heir to a financial empire! 3 mysterious girls also appear. How is this mission going to turn out!?

Ninja Action Manga & High School Love Comedy, all in one!

From Watase's Sorai:

This story is about "Yusura" who was left under a cherry tree 15 years ago. She grew up as a daughter of a pharmacist and works as a "Hikeshiya", who can erase sadness from people by using the Kongoumaru, which turns blue as it absorbs people's sorrows, then sends it back to the person guilty of causing the sorrow

From Esthetique:
As Yusura grew older, she acquired a reputation as the "Hikeshiya". Using her Kongoumaru, Yusura would eliminate sorrow from those who were suffering. Literally. One day, a nearsighted young man was being chased by several villainous looking fellows, so Yusura helped him. She took him back to her home,where she learned his name was Samon. Samon was the Daimyou of Sagami. Samon and Yusura have many interesting experiences in Edo Japan. The two run across many unique characters and with their aid have even more unique and exciting adventures.