Gomennasai.
A student hooks up with a woman for casual sex. They have an awkward meeting sometime afterward, in his classroom... because she's a substitute teacher.

Bousou Kiss

"...Gokko"
Brother and sister. A couple plays an incestuous game where they do perverted things to each other until one gives up.

Otoshigoro

One Step

Ferris Wheel
Sudo-san has a lover, who is two years younger than her, Takahana-kun. After receiving the news that Takahana-kun is going to be transferred, she thinks about how to work out their relationship.

Yume Musubi to

Hakuchu Yamu

Yoshi x Yoshi

Only One
Izumi Taeko is a weird and flighty girl, rumor has it you'll only need a coin to get your way with her, but is this true?

- Animexis

Reset

Ginga, who comes from a poor family, picks up Ouji, a son from a noble family. Soon after, Ginga tries to avoid Ouji due to their different lifestyles, but Ouji becomes extremely attached to Ginga, suddenly kisses him, and says "I love you!"

From Chibi Manga:

Hachiko is in love with her childhood friend. but he's now a popular idol...

From Blissful Sin:

1-4) Kanpeki na Koibito (A Perfect Lover)
The beauty, Shinohara, who just moved into the staff dorms, is misunderstood by his subordinate, Ueda, to be a masochist! Even though Shinohara tried hard to clear up all misunderstandings, his body seems to be addicted to the taunting eyes and commanding kisses, that he feels extreme exhilaration...?!

5) Then I Fell in Love (Oneshot)
Higaky Naoya, a successful crime novels writer, lives his life quietly and in seclusion in his big house all alone until he came across with an interloper.

From Ochibichan:

“Recruiting those who want to finish it and die, but feel sad doing it alone…”
Fed up with everything, Mie posted a notice on an Internet Bulletin Board and found suicide-partners. Four boys and girls were gathered together because of their ties to death. And then…?!

A collection of oneshots dealing with psychological themes like death, suicide and bullying.

A strange reunion, a strange toy store, a life-changing night...

1-2) Compassionate Coffee Shop
Working at a coffee shop gets boring for Kuhara until former coworker Fujinami comes by every night. Fujinami once kissed him after drinking, but Kuhara slapped him. Why does Fujinami keep coming by? And how does Kuhara feel about him?

3) Realize It!
Ogawa starts attending a boarding school, only to get the weird Hongou as his roommate. Hongou is always touching him, but does he mean anything by it?

4) By the Way I'm...
Reserved Machida has been sleeping with the over-confident Sakito for six months now, ever since Sakito told Machida he loved him. But Machida hasn't let himself get attached because Sakito's the kind of guy who can say that to anybody, right?

5-6) Sue (a guy), moves to Tokyo to go to college and lives with his mom's boyfriend's son, Kanai. Kanai is very cold, and doesn't seem to care if Sue's around or not. Four years later they're still living together, and Kanai starts dropping hints that Sue should move out. But Sue's fallen for Kanai...

After being abandoned by first her father then her mother, Yuu has become a girl who refuses to get close to anyone. There is one girl, however, who won't leave Yuu alone. The energetic, popular Ayumu inexplicably can't resist approaching Yuu at every opportunity. Will Ayumu be able to break down the walls that Yuu has created around herself?

It's Called Love is a romantic shoujo manga that consists of 5 short stories. Each story is done by a different author but in each you will experience the various expressions of love such as heartbreak, first kiss, etc. 1) To Be Your Number One by Ayu Watanabe 2) Sakura Tears by Keiko Suenobu 3) Special by Ikeda Yukio 4) Summer Love by Tsugumi 5) The Force of Dreams by Harui Yuna

The recently wed manga artist Kazama Ayami is drawing an essay on her true feelings about romance and marriage. She had minimal interaction with boys in her all girls school, but she got married with a boy she knew for a year, and now she must relive her embarrassing and pitiful memories for drawing her manga! Meanwhile, her rival manga artist is the boy she is about to marry, so will this become another embarrassing memory…!? This will be her challenge of appealing to other persons purer feelings!

From Fantasyshrine:

After his mother passed away, Kyousuke decided to live alone and transfer to another school. There he met a rather peculiar classmate named Kaname who’s unable to talk. Although Kaname cannot speak, he was able to somehow convey his feelings clearly through writing and facial expressions that made Kyousuke more drawn to him. However, Kaname’s cousin, Satoshi noticed the intimacy developing between the two which he could not approve… A sweet ardent, story of pure love unfolds…

Kugaya is a teenager who lives with his aunt, Sakuri.
The kendo coach at his high school, Narugami, has been after him to join the kendo team; but when he meets the new girl, Takemi, his life takes a supernatural turn and he is thrust into an epic battle with the demonic "Intruders".
Reincarnation... buried memories... the Holy Sword... "Himuka"... and the Clan of the Swordsmen... it's all too much for a high school student to bear!

From JShoujo Scans: Growing up on the wrong side of the tracks in Bend, Mississippi, Becky Lynn Lee doesn't have the luxury of dreaming. With an abusive father and a broken mother, she always thought that this was it. But after the ultimate betrayal, Becky Lynn can no longer live the nightmare. Determined never to go back, Becky Lynn escapes to Hollywood. As a photographer's assistant, she discovers a talent for spotting beauty and capturing the perfect shot. When the camera eventually turns on her, the awkward, shy Becky Lynn of her childhood disappears. But when the success she's achieved is threatened, Becky Lynn must find the strength to embrace her new identity and put the ugliness of her past behind her forever. Based on Erica Spindler's novel "RED"

From Broccoli:

Spirits known as kamui are thrown into chaos when the sacred spirit Okikurumi is taken from Atsuma's village, and the imbalance threatens to destroy Earth. Infused with the spirit of an ancient sword, Atsuma must leave his village to reclaim Okikurumi.

He encounters NOA, an organization of youths who wield the power of the kamui, and who may hold the key to Okikurumi. Atsuma is recruited into NOA by Sumire, a young woman with an empty soul who yearns for a miracle. Atsuma and his new companions must work together to find Okikurumi before the world is destroyed.

From Summer Rain:
Despite being the heir to a large business enterprise, Taichi Akamatsu wants to become a shoujo manga-ka and has just started living on his own in an old, run-down apartment. One day, Taichi was asked for help by the girl next door—her name was Midori. She reminded Taichi of “Midori,” his ex-girlfriend, but for some reason he still became interested in her.
This year marks the 10th anniversary of Ai Okaue’s debut as well as the release of her most recent work. Reading her work makes you want to fall in love again. A scramble romance comedy of friendship and love.

Yuu thought that love and romance were meaningless things... That is until she finds herself cross-dressing just to get a date with a cute girl. Can she keep up with her charade?

Your typical romance story between a girl (Konatsu Narumiya) and a guy...except that this guy changes into a pervy girl! He can only change into a girl during the night. Konatsu is the manager of the boys' basketball team, has a crush on the team captain. Unfortunately, the team captain is a complete jerk. When Konatsu confides in another team member, Haruki, about her troubles, their relationship grows closer. The only problem: Haruki is a nice ordinary boy by day, but a pervy girl by night!

From Chibi Manga:

She was her best friend and he was her first love...she didn't plan to change that. Ayu and Kaho were friends since kindergarten. They were the exact opposite; and even if both them were cute, they hated men. But one day, Kaho found someone she loved. "why? I was the one in your heart before..."
"Let's play at football" said a boy that Ayu never saw before. But, she felt her heart beating so fast and hurting so hard. It was the beginning of her first love...

Includes oneshots:
...Suki
It happened by accident... my first kiss, with Naohara-kun... 6 years passed, but that awkward feeling didn't go away.

Zutto Zutto Daisuki (I Will Forever Love You)
In the winter of my second year of high school, I had an unforgettable love. I really, really like you very much...but at that time I couldn't protect you. I'm sorry Ema.

From Chibi Manga:

Asuka, the ace of the volleyball club is training to become the best. But there's the devil coach, Nagano...