After dating a player who had another girlfriend, Rina decides to become a player also and immediately finds someone willing to be her lifelong toy.

From Tokyopop:

Daphne in the Brilliant Blue take place in a near future in which the remaining population lives in underwater cities, with waterways as streets. Years ago, while conducting underwater experiments, all contact with the surface was cut off. With the remaining human population now living underwater, The Deep Sea 9 Cities Association represent the last hope of mankind. Ai Mayuzumi is the daughter of the head of the research lab, and is an expert water jet bike driver. When the terrorist group Error, attacks the city, Ai becomes involved with the counter-terrorist group Stelnas, comprised of an all-female team, and led by a girl named Kei, and asks to join them. The group initially resists her efforts to join, but a surprising "gift" that Ai possesses, along with the way she handles herself during a kidnapping attempt, eventually sways the opinion of the members of Stelnas.

Akira and Yuujirou, who are childhood friends, both love to surf, and both have an unrequited love for each other. This is because after Yuujirou kissed Akira a year ago, she slaps him! Now all he does is bully Akira, whilst Akira has feelings of regret for slapping him!

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

From Fantasyshrine:

Since he first met Baron Kuroba, Seiji has been secretly in love with the master of the Kuroba Manor, where servants were rumored to be attacked by a vampire. However, Baron Kuroba only sees Seiji as a lap dog that needs to be disciplined for his carnal pleasures. How can Seiji convince the baron, who doesn't believe in love, to love him back?

This is a one-shot chapter from Oshiokiyo! an anthology of hard-yaoi BDSM borderline porn. Featuring a plot about two brothers from a small-time yakuza family whose parents are murdered by a rival family. Older brother becomes just like the enemies in the process of getting his revenge on them. Older brother-younger brother relationship devolves into top/bottom BDSM situation.

From Manga Abyss:

The 'starved wolf' man and 'little red riding hood' Shouji loved each other?

Also included in this compilation:

• Akuma na Cupid
Ashiwara Iroha has a crush on Suzuki-san. In order to make him like her, she climbs up a tree to try to touch the "legendary mark" at their school. He is supposed to fall in love with her if she does, but instead of touching the mark she falls from the tree and into Shindou Kaname's arms. He tells her "leave Suzuki to me" and becomes her devilish cupid...

Takato has been always bullied by his next door neighbor and physician Yasuyuki-sensei. One day, Yasuyuki's friend Kazusa comes over and Takato believes him to be his savior, but who knew Kazusa was a bully just like Yasuyuki. A one volume, threesome comedy.

A collection of short stories:

1. Oral Cavity Infectious Syndrome
On the surreal premise that women's mouths take the often weird shape of their partner's penis, Yoriko starts an investigation to discover with whom her boyfriend is cheating.

2. Local Tourist Information
A guide to an extraterritorial region of Japan.

3. Back Streets in Front of the Station
A girl goes crazy about reverse sides of different things, including streets, cars, and animals.

4. Genesis
Kago Shintarou's rendition of the Book of Genesis.

5. Superglue
What happens when you step on something so disgusting that you never want to uncover it?

6. Akutagawa in Front of the Station
A surreal homage to the writings of Ryunosuke Akutagawa.

7. When All's Said and Done - also included in Hell Season
A gruesome tale of hardened faeces, and a limbless girl.

8. Multiplication
Comic panels are multiplying and create opposing clans.

9. Abstraction
A two dimensional comic about young lovers turns 3D causing the characters' bodies to deform.

10. Blow-Up
What happens when every comic page features exponentionally more panels than the previous one?

11. No Need for Caution
The action of the comic happens outside of the panels--literally--in the white space.

12. The Memories of Others
Everyone's memories become visible via floating comic book panels.

13. Lord of the Ring
An incompetent sumo wrestler uses the powers of a forbidden pair of pants to overcome and shame his competition, until one day someone rises to attempt to crush him and take the pants for himself.

14. Spinning Thoughts
Wearing urinary calculi is the latest fashion trend.

Contains 5 stories: 1. ...Curtain. Living purely together with Sensei: Hiyori Okamura is a new mathematics teacher at a high school she graduated from. She still loves Shibasaki, a chemistry teacher who she loved as a student. One day, it happened that Hiyori couldn't use her room, so she moved to Shibasaki's room in the same apartment house, and began to live there. A curtain divided the room in two, and Hiyori and Shibasaki...!? 2. Love Duet: Honda Ema works with and is attracted towards Sawaki Koutaro. Honda plays the Piano and is taught by Sawakis little sister. But due to an accident Sawaki will be teaching her. 3. Sweet days for you, too 4. Impassioned Drawing 5. Entreaty Guidance

Bronte is running away from a failed wedding ceremony in the rain when she finds a cabin for shelter, occupied by a blood-soaked man with Gold eyes, who claims he just killed a man. His name is Mars West, and on impulse he kisses her, just as the police come to drag him away.

Five years later Bronte comes to New York to see Mars, who spent two years in prison for the murder it turns out he didn't commit. Then things get strange…

This is a soap opera of the highest order, with machinations and manipulations that only the very rich could get away with…

Based on Ann Major's novel, "Secret Child".

Eru Yamada can't seem to get away from the supernatural. She's being stalked by a vampire. Her teacher is a werewolf, who also happens to think she belongs to him! As if that wasn't enough, yet another boy with supernatural powers shows up, trying to get her to fall for him, and she winds up with a rival in love who has dangerous powers as well!

From Loveless:
Senke is a gloomy and shy man who's secretly in love with Masaharu, a mailman in the company he works for. His inability to confess to Masaharu leads him to lavish his love upon a Digital Monkey on his PC, which he names Masaharu. The recession, his low-paying job as a dispatch worker, and a demanding boss causes him to work overtime night after night. One night, fed up with seeing Senke working to exhaustion, Masahuru confronts Senke and in the process finds out about his Digital Pet. The stressed Senke breaks down and rapes Masahuru. After this disastrous incident, Masaharu avoids Senke. Senke works mindlessly and fulfills all the demands of his boss until he discovers that his Monkey Masaharu has died. In his exhausted state of mind and having a guilty conscience, he thinks this to be a sign, and dashes off to find Masaharu. When he finds Masaharu safe and sound, he is relieved and collapses.

From ShoujoMagic & Nekohana: A collection of short stories revolving around a girl's first time! Story 1: A Boy's Suggestion, by SHINJO Mayu Kana is on a mission of love. How pathetic would it be if a senior like her completed high school without ever having had a boyfriend? That's when Takuya, a freshman with a reputation as someone you don't want to mess with, confidently asks Kana to go out with him. She has misgivings about him being younger than herself, but can she be adult enough to overlook it? Story 2: Virgin Beast, by MINAMI Kanan See Ren-ai Shijou Shugi, volume 2 side story. Story 3: Let's Go Be Daring!!!, by AYUKAWA Mio Yoshino has a crush on Kanou and is too shy to tell him, but if she doesn't act quickly some other girl might. Yoshino's friend tells her how to becoming daring: Don't wear any underwear! This secret technique certainly catches Kanou's attention when a brisk breeze blows Yoshino's skirt up, and... Yoshino needs to come up with a good lie, fast! Story 4: When I'm with You, I Won't Be Home 'til Morning!, by KOUSAKA Yuuka After two months and three days of dating, high schoolers Eimi and Hiroto are finally ready to have sex. Eimi is nervous, but Hiroto seems okay. She heard that he's a real lady killer and his ex-girlfriend was his college-age tutor. Can Eimi -- a virgin -- possibly measure up to the kind of experience Hiroto has had? What will it mean for their relationship if she can't...? Story 5: The Awakening of Love, by SAKURAI Miya High school girl Asuka has a boyfriend who's 23 years old, Hiroyuki. When people comment that older guys must be better in the sack, Asuka confirms it -- but she doesn't honestly know... because Asuka is still a virgin. Unable to stand it any more, she gives it up to Hiroyuki (who didn't know she was a virgin), but instead of bringing them closer together, it drives them further apart...? Story 6: Smooch Smooch Smooch, by MASUZAKI Yoshino Tomo, age 16, has a crush on the university student Yuuji. They even live together. Problem: Yuuji is her cousin! He's never had a girlfriend, but that's because Tomo harrasses him in a series of various "attack" styles. As her latest attack, designed to make Yuuji jealous, Tomo and her friend Samata pretend to have a relationship when they're in front of him. But when Samata becomes serious about Tomo, Yuuji knows he has to make a decision -- fast. Story 7: Sweet Desires, by SHIGANO Iori Maya caught her boyfriend cheating... Since then she has lost faith in men. But will this change with a sudden kiss, outside a bar... from a kouhai??!!

From Attractive Fascinante:

“It’s fine if our hearts aren’t connected”, that is what Takamura sensei thought when he confessed to his student, Rin. But after a few times of bodily contact, Takamura started to desire Rin’s heart. Will Rin open himself up and accept Takamura?

A collection of short oneshots: 1) 17 Sai Natsu Aki connfessed one year ago to Yoh, but he was going out with someone at the time. So, when she finds out they broke up; what she does might be good at first. But in the end will she be happy with Yoh? Or will something go horribly wrong? 2) 17 Sai Fuyu Yui loves Maki, (childhood friend), but does Maki love her? During winter break she goes to her aunt's (where Maki lives) and confesses her love. Does Maki love her too? Or is she going to end up with a broken heart? 3) 17 Sai Haru One sentence is all I've ever wanted to hear from her. That's all. I love her. But I can't, I'm not allowed. She's my brother's fiance. Even so, I'll do anything to make her mine. If I hurt her, bring her pain, well, as long as I can be with her. I don't care if she hates me. 4) 17 Sai Aki Nao is in love with her Sempai. His brother confesses to her, and she uses him to get to the guy she likes. Will it work? Will she get her beloved Sempai?

From Heroines of Fantasia:
16-year-old Tsukimi Hina decides to get a part time job as a maid, and successfully passes her interview. One thing though: she can't use modern technology inside the house whatsoever?! Which means no vacuums, no cellphones, no laptops, etc. What is up with her twisted, but handsome, employer Asakura Shiyuusei-san? And what exactly is he hiding in his storage room...?

From Intercross:
16-year-old Hina's first job is with a 19th-century British enthusiast, Shuusei-san, as his maid. Even the way of cleaning has to be from the 19th century! Even so, this sweet gentleman makes Hina's heart beat so fast! There is actually another person in this residence, Mary Lou. She's as cute as a doll, but... she's, she's... a ghost?!

7 Short Stories About Sex (spanning across 11 chapters):

1-3. 7 Daime no Tomari (The Seventh Generation, Tomari)
Tomari is a cursed woman who must do specific sexual things with her partner or the curse will kill her. Her partner, randomly chosen by the curse, is a guy called Naoki. He's pretty much willing to do whatever she needs, but Tomari will have to get past his incestuous sister Kyoko first.

4-6. Hajimete to,
A teenage couple, Seriko and her boyfriend Ogihiko, find themselves caught in a plot from her crazy yakuza family to make them lose their virginity together.

7. Sandy Go Home
Yoko returns from studying abroad in America with her sex-crazed roommate Sandy, and they both proceed to fight over who gets to have sex with her brother.

8. Mete Yunde
After their parents died in a traffic accident, Morote's two older sisters became insane. Is he safe in the house with them any longer?

9. Pastel Ivory
School kids have a sexual encounter in a bathroom.

10. Ninjia Shoujo Makari Tooru
When a ninja invades a girl's bedroom, he finds himself completely outmatched by her skills, both ninja and erotic.

11. 80D
A couple has a sexual exploit in a library after hours.

From Midnight Scans:

A quiet girl falls in love with a fourth year ikagu club member, Koushirou-san, who is a kind, serious, and charming person... But then... why would he...!?

From Condensation:
Toujou Souko attends a Catholic high school for girls and spends most of her days ditching class and trying to hook up with guys. She's in a hurry to fall in love and often gets into trouble. Ueda-sensei is Souko's homeroom teacher and all the girls idolize him on campus. He thinks Souko's a good kid and is looking out for her best interests... Yet he never meant to encourage her to try and seduce him...
What begins as a passionate affair becomes a true and undying love... Ai Girl is an angsty love story loaded with melodrama. It should be noted that this series has adult themes and high smut content.