From Shoujo Manga Maniac:
That man will take away both your heart and your body, together with the jewels... Kaitou Crow is a beautiful, unidentifiable young man who's only after jewels. Ruri, the daughter of a jewel designer, accidentally saw the kaitou while he was going for a preliminary inspection. While snatching away Ruri's first kiss to seal her mouth, Crow announced that this time, he would steal both her heart and her body, together with the jewel ... ? The dangerous love mystery of a conceited, forceful, beautiful, young, and perverted kaitou!

Since the characters of this volume are the same of the other 3 volumes, you can consider this as the 1st volume of the series!

Includes extra oneshots, Kuchizuke wa Amai Bara wa Kizuato and An Easy Mystery Better Than A Kiss.

Nakanishi searches for the truth about a classmate's murder so he can settle a grudge for her.

From AQUA Scans: Elite Development Education Academy, Noblesse Oblige. The grandson of the academy's chairman, promised heir as the next chairman, Inaba Hakuto. The kind-hearted, younger brother who supports him, Inaba Kokuto. However, with the chairman's death, the fate of the twins begins to greatly warp. The one who holds the key is, the demon who resides in the mask... Masquerade...

This award-winning classic story focuses on Marlee, an agent of the space empire sent on a mission to track down the opera singer Eroccus. There are three intertwining narratives which span planets and hurl the readers back 30,000 years in time. The narrative takes place in a non-linear fashion, unfolding across space and time, before folding back upon itself at its culmination.

Note: Winner of the Seiun Award in 1983.

Note 2: Gin no Sankaku was not serialized in a manga magazine. Based on content, it could be considered either seinen or josei.

A collection of four short stories.

Suna no Ue no Rakuen (砂の上の楽園)
Yoru no Mori no Soko ni (夜の森の底に)
Boku wa Tabi o Suru (僕は旅をする)
Ame ni Nareba ii (雨になればいい)

Chapter 1 is the 100-page title story. It's a supernatural fantasy tale about a man with one chance to escape from death, a mysterious woman he meets, and a tribe seeking to find its way back into Heaven.

Chapter 2 deals with the mystery of a man gone missing, and presumed dead.

Chapter 3 is a very short story about a couple in the mountains who pick up a strange guest.

Chapter 4 is a longer story about the traditions binding a family, those that would break away from them, and the dark secret that holds the family in sway.

Erika Klause was separated from her brother when she was little. Determined to meet him, she decides to enroll at Rosenstolz Academy, where she is sure that she will find him. But, on the first day of school, she accidentally meets the five Strahl candidates. Since assistants of the Strahl candidates gain access to the boys' dormitories, Erika becomes determined to become an assistant in order to find her long lost brother. What awaits Erika at Rosenstolz Academy?

Yuki Kaori only did the original character designs.

From Storm in Heaven:

Possessing extraordinary detective skills and even helping out at the police department can't be normal, and anyone who knows Uryuu Nanao knows that she's different from the rest. It is this distinctiveness that draws both Karasuma Nozomi and Sakuragawa Nozomi to her despite Nanao's attempts to distance herself from them both. However, a series of murders take place and Nanao is forced to enlist their help in order to unravel the truth behind her father's murder. Just who is the real mastermind behind the ongoing murders and why are they targeting Nanao? And what is the secret left behind by Nanao's father?

Sawatari Ai is an insatiably curious high school student. One day, she notices that a boy named Akizuki Tooru has joined her class, but according to her friends, he's always been around! He was a childhood friend of hers, so why doesn't Ai remember him? But the weird thing is...Ai's memory lapse isn't the only weird thing. She's about to be faced with hyper psychic action!

Note: Volume 2 only has one chapter that deals with the main story; the rest of the volume consists of unrelated oneshots.

Dusk Is Twittering (Tasogare wa Sasayaku) - Is a school story about a boy--who draws--that transfers to a new school for follow a girl he has a crush on. Unfortunately for him, she already has a boyfriend.

The Sound of Melting (Tokeru Koe) - Is school life story about a girl that dislikes her own voice due to being compared to her mother, who is a singer. Despite this, she loves to sing. So, there is a boy the sends her slips of a love letter after her voice lessons based on her voice.

Midsummer's Criminal (Natsu no Ran) - About an adult that tutors a 6th grader, who looks like an adult.

From Baka-Update: Russian bodyguard Alexis is given the task of hunting down famous art thief Shiro, but is intrigued by art researcher Kairi. In a world of lies, intrigues, and espionage, love can be a deadly illusion...

In the Mimi (w)o Sumaseba series:

V.1 - Mimi (w)o Sumaseba
Shizuku Tsukishima loves books. One day, she notices that the name Seiji Amasawa appears on the checkout cards of nearly every book she's borrowed! Before she realizes it, her heart is pounding for a boy she's never met... and that's when a mysterious black cat and Shizuku's sense of wonder guide her to an unusual shop--and introduce her to someone she's been curious to meet! Amazing things can happen...when you listen to your heart.

- ShoujoMagic

V.2 - Shiawase na Jikan
Two years into the future, and Shizuku is now preparing for her entrance exams. The second story, "Kikyou no Saku Koko" (The Blooming of the Balloon Flowers), is an unrelated original story. Tsuge Takayuki is a normal college boy, who, one day, sees a girl admiring the flowers in his front yard, and was reminded of a girl who stood by the flowers one year ago, crying in the rain. He falls in love with her, but will her injured heart accept his feelings?

Manga adaption of H.P.Lovecraft's "The Haunter of The Dark" and "Dagon"

The story is set in Providence, Rhode Island, which is author H. P. Lovecraft's home town and a common setting in his books. Robert Blake, a young man with an interest in the occult, becomes fascinated by a disused church in Federal Hill. His research reveals that the church has a sinister history involving a cult called the Church of Starry Wisdom and is dreaded by the local inhabitants as being haunted by a primeval evil.

Jae is a Korean student who came to Europe to study art. Things aren't going her way, but she's determined to make it. One night, her friend Melissa brings a drunk guy to her apartment and asks if he can stay there for the night. Jae doesn't like it, but agrees. That night she has a dream that the drunk guy drinks her blood... which, of course, turns out NOT to be a dream.
Jae is surprisingly unafraid of the vampire, Michael, and starts to paint his portrait. The two strike an unusual deal: if Jae allows the vampire to feed on her, he will pose for her. His beauty and alluring preternatural energy could be exactly what Jae needs to finally succeed as a painter.

Contains the side story: Scissors

This is the one shot of the movie that Sana and Naozumi starred in from Kodomo no Omocha.
A 14-year-old boy, after the loss of his parents, starts researching his older brother, who has mysteriously disappeared several years before. He finds him in a strange palace, with his two friends who had also disappeared. At first, the boy is happy, but then he discovers that something horrible has happened in that palace, and he might just become a victim too.

This collection of horror short stories includes tales of murder, romance, and the supernatural.

The title story follows Natsuko, a maid at the Hagiwara mansion who bears an exact resemblance to a recently deceased woman of the household.

Other stories include a cat who watches for his master and a ghost, a work of art which leads to revenge through possessed bodies, and a woman who haunts the husband who murdered her but whom she still loves.

The mood and pacing of these stories are a kind of Japanese gothic, steeped in the culture but as clear to readers as the passions we all share.

Kazuki can't believe that he slept with a fellow cop, Seo-senpai, but the more Kazuki tries to pull away from him, the more Kazuki desires him. It is a story about one stubborn uke.

Rumours about a werewolf appearing on nights when there is a full moon quickly spread through Bato’s school. Bato suspects that his strange roommate, Kadirael is the werewolf, but Bato gets an even bigger surprise when he confronts Kadirael about his true identity.

From MangaHelpers:

The world is in a tense political situation, and one country has instituted a new mandatory education program for all children fifteen and up. It's a half-year program that puts the children through military training. Kazuki has traveled to an installation on Yurikago ("Cradle") Island for his half-year of training along with many other boys. Kazuki has no special physical talent, but he has a remarkably good memory. His closest friend in the training, Sai, is top-notch at everything and not particularly liked by some in their class.

One day, their relatively ordinary life in training comes to an abrupt end. Kazuki awakes to find the island facility in ruins. He has no idea how much time has passed, or what has happened. Soon he meets up with Sai and a strange little girl with a cat, and they begin to try to figure out their situation. What has happened to the island, and to their country? [tethysdust]

When Aoko was four, a meteorite struck her town. It then rained for twenty days straight, and the crater became what’s now known as the Twenty Day Lake. Two decades later, Aoko can’t remember the day the meteorite fell, or anything of her life in the town beforehand. And so she dives deep into the lake, searching for that something in her memories that she can’t let go of…

From The Zero Alliance:

The temple protects the City of Sound by having hymns sung every day.
But why does the sound echo throughout the temple? Why does the song seem like a requiem?
And why are the hymns so important that…. the city will collapse if they stop?!

This is the story of a prince, Izegole, the sixth son of the Agon family. The family that years ago took control of all the 500 villages of their continent. Izegole and his brothers and sisters are in charge of security in all the villages while the king, their father, takes care of politics. But one day everything changes, when a killer is sent to kill Izegole, a God comes to Earth with a secret mission and one after an other, his World, all that he considers important crumbles before him and leaving him but with hobson's choice: fight or fall? What will he choose? (find more info at the link: http://myselfmanga.webs.com/)