From Vertical:

From the author of the New York Times manga best seller Chi’s Sweet Home comes a delightful series of vignettes in the life of a kitten and her doting owner. To a young kitten, even the most mundane things appear fresh and exciting (and sometimes unpleasant or scary). Join FukuFuku on her journey and rediscover the world from a tiny cat’s point of view.

From The Cat Mummy's Page:

A story featuring the everyday life of a domestic cat owned by an old lady who runs a local provision shop. Very very funny, if you keep a cat, you identifies with everything the comic's trying to tell you.

Note: Volumes of the original edition are "numbered" according to the Iroha poem, rather than with actual numbers. (That is, い ろ は に ほ へ と ち り ぬ る を (i ro ha ni ho he to chi ri nu ru wo) instead of 1-12.)

One day, a ronin student on his way home gave a bentou to a cosplay cat girl. Unexpectedly, the cat girl then decided to stay at his house, resulting in the two living together. But then, the girl turns out to be one of the mountain shrine's Gods…

Having to deal with the girl’s magic plus the teasing from other cats and Gods keeps the main character’s hands absolutely full. Will he ever get a break or will this “big pet” burden him forever?

Kanna Haruhiko (male), for reasons unknown to him, is suddenly turned into a girl.

He returns to his male form some time afterwards, but with the continuing cycles between turning into a girl and then back to a guy, he is bewildered by the differences in both physical aspects and ways to communicate with other people.

Plus the abrupt changes that happen to his relationship with other people including his best friend and his childhood friend.

A dramatically depicted story about men and women...

Their city is filled with criminals and three incredible high schoolers. Yugo, Rikiya and Tasuku are determined to clean up the city with whatever means necessary, even if that means using violence.

During a typical night of wiping out gangs, Tasuku comes across a beautiful girl held prisoner. She helps him survive what would have been a mortal wound by allowing him to see the future. Tasuku takes her home where he finds that her name is Noah, she doesn't speak at all, and has no memory. Even more fascinating to Tasuku, she bears the same tattoo as the person he has been searching for years for.

Three quarters of the world is the world of the dead. The world has been invaded by phantoms. One day, a boy named Nagi finds in the mountains of scrap wood a mechanical teenage maid girl. He immediately takes her home to repair her. The first things that Elise, this mysterious mechanical maid, says is, "Good morning, Nagi." Who is this mysterious silver haired girl? The fate of the world rests in their hands.

From Tokyopop:

Yuuki is an energetic teenager who carries the disturbing power of foresight in her dreams. She finds that this is tied to the mysterious Deep Sleep that has overtaken her sister, Yuuka.
Clues left on her cell phone and visions that come to her in her dreams begin to reveal a strange puzzle... and then in one dream, a glass wall stands between her and her sister while a faceless little girl stands by Yuuka. The mysterious girl hands Yuuki a kaleidoscope--which Yuuki discovers she still has when she awakens from the dream the next morning...

This story take place in a small village. Highschool student Inami Kazunori accidentally found out the secret of the newcomer, Udagawa Akihiro. In return for keeping quiet, Inami asked Udagawa to become close to the girl, Yoshimura, who Inami's best friend, Maruyama, likes. However, Inami ended up feeling bad about it and Udagawa revealed his secret to the class himself?!

From mochi*mochi: Morimura Yuuki, concertmaster at Fujimi Citizens Orchestra, loves music and his small, amateurish, but tight-knit group at Fujimi. His world is shaken up when a brilliant, new conductor, Tounoin Kei, is recruited to breathe life into their music and orchestra. Yuuki feels Tounoin's high demands will do nothing but chase away the members, but when he draws more from them than they ever thought possible, Yuuki reconsiders his own motives for staying at Fujimi. Obviously, the newcomer Tounoin understands Fujimi more than Yuuki ever did and even has the girl that Yuuki's been in love with for the past three years, at his feet. Nursing a wounded pride Yuuki resigns from Fujimi, but Tounoin has other ideas...

In the Fuhoni! (Unwilling!) series:

V.1 - Fuhoni!
Hikawa Chihiro had always been a flirt until he met his match, Jyounouchi Haruhisa. Being the older one, he wanted to change the fact that he was the one being held. While having internal conflict, the appearance of a new younger rival, Koide, made Hikawa realized he had to be honest with himself or to risk losing Jyounouchi. What would he do?

V.2 - Ran
The continuation of Hikawa and Jyounouchi. What happened when Jyounouchi nii-san tried to break them up? When Hikawa found that Jyounouchi's new neighbor, Toba Kouhei, was his ex-classmate, he refused to go to Jyounouchi's place again. Toba asked Hikawa to join him as his business partner. What would Hikawa do?

V.3 - Goku

Yoh is the only human being living in a strange town that exists somewhere between this world and the Twilight World. Residing in this town are spiritual manifestations of real world objects that were forgotten or thrown away by men. Yoh is the owner of a lifelike doll named Ian, who has the special ability to take photos of other beings' memories. With her help, he is running a photo studio called "Fuguruma." The manga revolves around those specters who seek the studio's service and the stories they have to tell.

Miyano Amata, known as the "Perfect Prince" for his intelligence, looks, and cool personality, is asked to substitute for his sister as an attendant at a doujinshi convention disguised as a loligothic girl. There he meets a girl from his class and they become friends, but he must crossdress in order to be with the girl while learning about the fujoshi fandom.

Notes:

? Fudanshi = BL fanboys: Some may be gay, some may be straight. More info can be found here.

? Fujoshi = (Literally) Rotten girl: A pejorative Japanese term for female fans of manga and novels that feature romantic relationships between men, often with the implication of yaoi concept.

Huffman Island is a land that emerged from the deep due to volcanic eruptions over three decades ago, now, it is split by an uneasy cease-fire between two major world powers, the USN (United States of the New Continent) and the OCU (Oceania Cooperative Union).
The cease-fire has held for 20 years, but now tensions are mounting, and it looks like open war will break out again soon. Matsuda Akira has gone to join the on-site reporting team for NNTV.
Are he and his colleagues really ready for the horrors they may face if they're caught in the middle of a war?

From Sweet Indulgent:

To a person, ?life? can be?
a picnic on a sunny Spring day,
or a battlefield on a freezing Winter day?

For some, it can be like heaven?
Or for some, it can be like hell?

What can a charm book do for a girl in love?

Youta was living with his big brother when a guy named Takamasa, a colleague of Youta's respectul brother, suddenly stepped into their life and after a bet, tried to seduce him... ~from Countless Time

Love Momozono is a 14-year-old student at Yotsuba Junior Highschool that tends to care more for others than for herself. One day she visits a show of the famous dance unit "Trinity" and decides to become a dancer, too. On the same event, subordinates of the Labyrinth Kingdom show up who want to collect the unhappiness of the audience. Love gets the power to change into Cure Peach and fights them. Soon after, she is joined by her good friends Miki, who is Cure Berry, and Inori, who becomes Cure Pine.

Hachiman Hikigaya is a high school boy with twisted character. He prefers to go against the trend and refuses to make friends with anybody. In order to get Hachiman back on the right track, his school teacher Shizuka Hiratsuka forces him to join the "Public Service Club." There he meets other problematic students.

From Etc:
Dr. Katou is an ambitious woman who seeks to revolutionize the corrupt and inefficient Japanese medical system from within by becoming a professor in a teaching hospital. She enlists a maverick surgeon, Dr. Asada Ryuutarou, to help her with research that would catapult her to a professorship should they succeed and publish. However, Asada's refusal to conform to the system soon threatens to destroy not only her plans but her entire career. Katou is prepared to do anything, including going along with the system, in order to achieve her end goal, but she begins to question whether she has gone too far as Asada's actions bring many of the system's shortcomings to light.

Note: Won the 50th Shogakukan Manga Award for general manga in 2005.

The Great Tokyo Earthquake. Ten years ago, it destroyed lives as it tore buildings asunder. Among those who lived through the disaster was Ganta Igarashi, now a middle school student finally getting a footing in his own life... that is, until the day the 'Red Man' appears at his school and turns his world upside down again. Ganta's entire class is brutally murdered, and although innocent of the crime, Ganta is sentenced to death and sent to the bizarre prison known as 'Deadman Wonderland.' There, a brutal game of survival begins, where Ganta must discover the truth behind his classmates' murder.
Can Ganta break out of Deadman Wonderland... or will it break him first?

A collection of stories: Chapter in order

1. Oboreru Sakana (Drowning Fish)
Living in a house of constant fights, An has learned to drown his feelings in the water. He has never felt love, and doesn't desire it - people call him cold. Usami, the illegitimate son of a wealthy business man, is a player who dumps his girlfriends when they fall in love with him. He doesn't deserve to be loved... How can they love him, when he doesn't love himself? Will the fish be caught by the lonely net, or will each sink to the bottom weighed down by unrequited feelings?

2. Rakuda Tsukai to Ouji no Yoru (Night of the Cameleer and the Prince)
Kamel is the only white skinned boy in the caravan. Because his skin is weak, he often gets fever and feels bad. He has the camel named Sadiku, but still he feels a little lonely. And one day he finds a passed out man in the desert who is...

3. Ibitsu na Kakera (Broken Pieces)
A story about a flame of unexpressed feelings, controlling and eating away into the blood relation. A brothers' forbidden love.

4. Kusatta Rasen (Rotten Spiral)
What is the true relationship between high schooler Ataru Koganei and the famous actor Shuu Kanai?
Koganei appears also in Ienai Itami o Daite Iru.

5. Ayaui Kyouen (Fragile Play)
Chapter extra of characters from Ibitsu na Kakera and Kusatta Rasen.
Features Makino brothers from Ienai Itami o Daite Iru.

6. Rakuda Tsukai ga Kieta Asa (The Morning that the Cameleer was gone)
Chapter extra to Rakuda Tsukai to Ouji no Yoru.