It was the roaring 20's, and the country was Japan. Bluecat, or Aoneko, is a debonaire aristocrat with too much money and leisure time. Along with his servant boy Tigerman, he dabbles in private detective work much to the chagrin of the real police detective Mr. Bee-Prince (Hachiouji). Bluecat is handsome--and yes, he knows it--witty, polite, and popular among the rich. However, his deviant libido, as well as his own attractive nature, often land him in danger.

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...

Kakuriyo Monogatari takes place in an ancient city where only spirits live, and no human knows that this city even exists. Join the story of the spirits, the tale of the afterlife!!

Mikami Tsubasa has been away from school due to a heart condition. On Christmas Eve he decides it's time to start a new life and runs away from home!

But before he can get far his childhood friend, Gin, gets into a serious accident. Tsubasa, in desperation, pleas for someone to help his friend. His call is answered by someone rather unexpected though, someone calling himself an "angel"...

The boy who had everything taken away by the Novus Orbis Librarium which monopolizes power and governs humanity, obtains absolute power and declares war against the world. The story behind the possessor of the Azure Grimoire, the "Grim Reaper" Ragna the Bloodedge's battle begins!

Content in the tankoubon:
「逃亡急行」 - Toubou Kyuukou (Escape Express) (published in Petit comic, 05-07/2003)
Magazine reporter Natsumi comes across the scene of a murder and is captured by the youth who seems to have committed it. He insists he's innocent and the two go off to Switzerland together in pursuit of the real murderer!

「失踪都市」 - Shissou toshi (published in Petit comic, 01/1996)

「サルでもできるガーデニング」 - Sarudemo Dekiru Gardening


In the Bunkoban:
It has everything, but Sarudemo Dekiru Gardening, instead it has:

「死刑台の72時間」 - Shikeidai no 72-jikan - 72 hours of death stand (was also published in Umi ni Ochiru Tsubame)

「買って飲んであそんでデンマーク」 - Katte Nonde Asonde Denmark (Omake)

From Acme:

An Inoue Nawo title that focuses on a man whose job description includes disposing of dead bodies and the stray who blackmails him into sheltering him.

Resource depletion, environmental contamination, desertification, and foolish wars. Mankind willingly walked along the path of annihilation. And at the end of that path, those who survived relied on the power of science and conducted endless experiments to obtain the valuable source of life. As scientists are exploring the desert's fallout areas, a child-like being is found naked on the ground and was brought into an underground survival refuge. As they analyze the child, what will they discover?

Shira, 17 years old, a student who loves Manga and consider it as his only friend. He always gets involved in fights and loses them. Oneday, on his house balcony, he sees meteors heading toward him. That was the beginning of his adventures along with his 'Friends' in order to rescue the world from the 'New Terrorists' organisation.

Two friends on their vacation decide to take a bath...

Based on Yukkedoluce’s popular song The Transient Apple Salesgirl: What would you give up for a chance at eternal life? Money? Friendship? Memories? Most people would consider it, if not actually go through with it. After all, immortality gives you an endless amount of possibilities… And yet this story tells a tale of a boy who considers to give up his immortality for just one thing - the friendship of a stranger…

There is a planet where all the inhabitants have mysteriously disappeared. This planet was called "Earth." Four people (Shiki, Miyuki, Yoshimura, and Satou) are dispatched to investigate the planet, its remaining living things, and the remains of the culture that once thrived there. Together, they pass peaceful days on the quiet Earth.

From Clamp no Lumiere: Albert de Morcerf, 15 years old doesn't know what's the right future for him... in other words he's your average teenager. Despite his money and the glorious name he's caring (he's the son of a famous general) he feel a bit lost. Between Eugenie, his fiancee, he's not sure to love and Franz, his over protecting best friend, he's living a carefree existence... But everything is about to change when Albert crosses the path of the Count of Monte Cristo, a mysterious gentleman, rich beyond anyone else dream. Who is this man? Why does he seem to know everyone's darkest secret? From Del Rey: While vacationing Luna, Albert, a young Parisian nobleman, meets the Count of Monte Cristo, a fabulously rich aristocrat from the far reaches of the galaxy. Fascinated by the count’s sophistication and intelligence, Albert is unaware of the older man’s dark purpose: to enact revenge for a terrible act of betrayal committed against him twenty-five years ago. Soon, all of Paris, including Albert’s own mother and father, will feel the terror of the count’s vengeance.

High-school student Nanamura Hikaru has little memory of his deceased father, a famous playboy actor, until his father's suave attorney, Shimogura, contacts him with the promise of a sizable inheritance. The catch? Hikaru has to make contact with his eight half-brothers - the fruit of his father's philandering ways.

From Eternal Bunny Love:

Colors. Death. Life. Questions. More questions. Will they be answered? Maybe a Roman could shed some light...

Based on an album of the same name, by the band Sound Horizon.

N/A

Story 1: A young woman who fell into a time slip.

Story 2: A group of young people who was hiking get stuck at an old shrine because of bad weather, and one by one they are killed by a moster who was sealed at a cave below the shrine.

Story 3: A group of people met up to tell their own horror stories.

They have been maintaining the balance of Yin and Yang since ancient times. Whenever the world is in chaos, there are many cases where evil spirits come to do harm to humans. The gods select talented humans and they are given their own guardian god for them to calm the over flow of Yin. This has continued all the way up to the present, so those that are chosen by god are hunters that eradicate ghosts, they are called Ghost Hunters.

From MAL: The story is set around shimatsuya (person who collects unpaid debts for prostitute houses) Saitou Ritsuke who is asked to look into ghost rumours surrounding one prostitute house.

A rather morbid, sombre manga about two high school students, Kamiyama Itsuki and Morino Yoru, who have a peculiar interest in deaths and especially in murders that are committed near to them. Due to their strong fascination with murder and highly-developed analytical skills (along with some luck), they manage to solve the murders that have even eluded the authorities. However, acting on their own sense of justice and in self-interest, the murderers are often able to escape with the murders that they have committed. Often, it is Kamiyama that solves the cases even to the most subtle of details, but he is only interested in one thing, and that is the method by which Yoru should be killed.

Note - Regardless of appearances, the fact that this was serialized in Shounen Ace makes Goth a shounen manga.