from -dokidoki- :
Ichirou's best friend Naoto's noticed that he's been acting a bit unusual since summer vacation. With a bit of best-friend solidarity, Naoto squeezes out the tale of Ichirou's secret summer fling: a sexual encounter with a mysterious stranger fleeing from a rainstorm. Naoto is, naturally, scandalized, but not half as scandalized when he and Ichirou run into the summer fling again at a school festival...

As if a guy falling in love with another guy wasn't complicated enough! How about when that boy's already got another guy after him? Throw a live-in cousin with an aggressive crush and the world's cutest lovestruck best friend into the mix and the situation gets rather convoluted, even by Koide-standards.

From Fantasyshrine:

Under the cover of the night
In the silent harbor
Two lovers, lips sealed on each other, reunited after two long years…
True love never dies…

The hero in this manga has a split personality and each personality has its own lover! Aki is a right-hander and seme (but he denies his homosexuality); Ao is a left-hander and uke (acts as the "bad guy" and reduces Aki's excess stress). One personality is afraid the other one will take over and destroy it. In the end, which will win? Ao feels he will be deleted by Aki and asks Sayuu to help him...

Tsubasa and his teammates want to win the World Youth, the under-20 world cup. They discover new talented teammates, but also new rivals in Asia and in the rest of the world, and this time, Brazil will be here...

A one-shot taking place after the Captain Tsubasa manga and before the manga World Youth. Tsubasa isn't in Japan anymore, the High school national championship is ending, and Japan's players will make three friendly matchs against the Hollanda Youth.

After the World Youth, Japanese players are looking for pro careers in Japan and around the world.
In order to fulfill their dream of World Cup 2002 in Korea and Japan, they must get stronger playing in various club competitions, home and abroad.

*Includes a side story called Go for 2006 in vol. 15.

The continuation of Captain Tsubasa after "Road to 2002".
Are they now aiming for the World Cup, Tsubasa's dream? No, Misaki has also a dream: win the golden medal in the olympics, and Tsubasa promised to help him.

From Scum-Scans:
11-year-old Tsubasa Ohzora transfers to his new school where he quickly becomes the star of the school's soccer team. His Brazilian coach, Roberto Hongo, notices the potential of the young athlete and soon offers him a chance to come with him to Brazil. Young Tsubasa trains more and more and is with each passing game more confident in his abilities. Old enemies become his friends and the World Cup seems closer and closer for him.

1. Canvas ni Kuchizuke (w)o (Kiss to the Canvas)
Chapters 1-3 tells the story about the explosive encounter between a boy who loves that people watch him and an artist who loves to paint.

2. Canvas o Dakishimete (Embracing the Canvas)

3. Canvas ga Itoshikute (The Beloved Canvas)

4. Itoshii Yubisaki (Beloved Fingertips)
Kazune's childhood fascination with harpsichord tuner Takayama's fingers has grown into an obsession over the years. Now a high school student, how long with Kazune be able to repress his feelings for the cool Takayama?

5. Goshujinsama to Yobanaide (Don't Call Me Your Master)
Being mistaken as a girl and groped often Midori is getting sick and tired of it. Then came Fujita who is kind and keeps his distance no matter how much Fujita truly wants to touch Midori. Knowing this Midori is touched that such a guy exists. With this will love blossom and what's this... Midori is Fujita's... master!?

6-7. Kitsune no Yome (Bride Fox)
During a summer festival in middle school Akane is cornered and molested by a guy in a fox mask. It's also the night his best friend Kyouhei stopped speaking to him. It's three years later and Akane still can't move past that night, the unwilling pleasure he received at a stranger's hands, and the look on his best friend's face when Kyouhei saw Akane's ravaged body.

From Dan of Population GO:

"This charming story follows Kanon Miyamoto who, ignorant of her popularity, is confessed to by Bessho Chiaki, the school's most intelligent and beautiful girl."

From Aerandria Scans:

Kayuu, a doll-maker who was murdered six years ago, made living dolls at the request of clients. Mitsuki, his daughter who is still finding out the mystery to her father, together with her favorite student Yue, are faced with countless ordeals. What is Kayuu's hidden secret?

Two twin brothers Ry and Key were trained in martial arts since childhood by their Martial Arts father, "Rokuu Riley" as they are now young adults a tournament begins in their city and they feel they are called to accomplish something much greater in life. And in their own ways they will not stop until they have succeeded no matter what challenges, threats or obstacles come into their lives.

Older brother forces younger into a sexual relationship after their parents' death.

From Infinity Studios:
Ever since we were children, we’ve heard stories about ghosts and about heaven and hell. Well, what if we told you another existence between heaven and hell exists? This is exactly what Suh Rin, an average high school girl, finds out one gloomy day.
On her way home from shopping around, Suh Rin meets with an unfortunate end when she is hit by an on coming truck. The next thing she knows, she’s being abducted by a stranger. Overwhelmed by the fact she had just been killed, Suh Rin has difficulty grasping the fact that she has entered a new existence in a realm of spirits. More importantly, she has yet to realize that tremendous supernatural powers lie within her… a power great enough to make her the target of abductions by tremendously powerful people within the spirit realm.
However, thanks to Young and the mysterious owner of a café called the Café Occult, Suh Rin is rescued from a new existence as someone’s servant. On the contrary, she joins Young on action packed thrills in which she assists Young fulfill requests as an ‘errand boy’ taking care of special requests by clients in a lawless world controlled only by power.

Tomoe Tatsumi is a freshman attending university in Tokyo. Life couldn't be better: he's living in a really nice apartment for less than most people pay for a single room. This is all thanks to Mitsugu Kurokawa: salaryman, landlord, and (hopeful) lover.

It is due to Kurokawa's generosity that Tatsumi is able to live in Tokyo on such a tight budget. Kurokawa's intention is clear: to love, honor, and cherish Tatsumi until his dying days! And if big brother Souichi Tatsumi has his way - that day will come sooner than not!

For Kurokawa, progress can only be made by "challenging the impossible...." And thus, Takanaga sensei introduces us to her charming romantic comedy, Challengers!

- DramaQueen

The main couple from Koisuru Boukun also have a few short chapters through out the manga that take place before Koisuru Boukun starts.

A manga consisting of a 9 chapter story with 3 side stories.

Shinju no Kusari (Chain of Pearls)
The beautiful, genuine pearls we lust after belong in a chain... because that is how they bind our hearts. Hisa, the newest manager of her high school's soccer club, has a secret: a part-time job. If anyone knew, she would either have to quit the job she needs to survive or the sport that she loves. Sakyou, one of the team's most talented and anti-social members, finds out about Hisa's secret... so it's a good thing for Hisa that the handsome and high-handed Sakyou wants to keep her close to him! Or is it? (There is an additional one-shot of this story in Vol. 1 of LoveSupreme Principle)

A "Girlfriend" with Substance
(scanlated as The Fruit Called Grapefruit)
Minami Kanan's debut work. Sachi was so determined to become Takanori's girlfriend that there was no way he could say "no." Literally, no way. She's the girlfriend he was forced to have, and he treats her as such. They go out together, but it seems obvious that Takanori hates every moment of it. When Sachi finally has enough of his unaffected attitude, will it make Takanori happy to be alone again?

Unconditional Love Formula
Tachibana Kouya is a whiz kid, while Ayumi barely passed the entrance exams. They're at opposite ends of the spectrum, but Ayumi is determined to win Kouya's love by having him tutor her -- then, when she passes the physics exam, she's going to confess. Why would Kouya want to tutor such a poor student, though? Ayumi's love rival discovers that Ayumi had to bribe Kouya to do it, and so she feels no remorse when she ruthlessly foils our heroine's efforts to succeed in physics and love...!

The Rumored Natori-kun
High school freshman Ai just found out that the stranger she fell in love with at first sight is the notorious Natori-kun, who goes to her school and is rumored to ditch every girl he agrees to date. That doesn't discourage Ai, though, because he's been nothing but nice to her so far. What will it take to become Natori's girlfriend, or is Ai doomed to become just another rumor?

From Easy Going Scans:

Kei often gets involved in fights, despite of him being weak and always end up losing… One day, while helping a friend to bring some textbooks to an old building of his school, he and his childhood friend, Tomoe, are attacked by a monster. In order to save his friend, Kei will choose to become a Grave Protector!

* Cerberus, in ancient Greek mythology, was a hell hound that guarded the gates of the Underworld preventing those who have crossed the river Styx from ever escaping.

From DrMaster:
Supernatural phenomena and strange occurrences are no sweat for the Nanami Paranormal Investigation agency, headed by Asagi Nanami. As "freak" activity grows to a terrifying fever pitch, Asagi's assistants -- Naoki, Tokiko, and Mahime -- help to solve several major "freak" cases. Freaks are creatures with the ability to possess humans and prey on their weaknesses. However, Asagi and his gang are no ordinary humans; each is equipped with a special power to vanquish Freaks.

From Condensation:
The story centers around Keito Aoyama, a former famous child actor. Due to a childhood incident, she retired from her career early and withdrew from normal society. Now 16, she passes her days in boredom and without purpose. But one day she runs into a stranger who takes her to El Liston--a free school for high school students like herself, who don't have a place where they belong. Though hesitant at first, Keito decides to enter El Liston and subsequently, she begins a new stage in her life. With the help of her only remaining childhood friend, Taiyou, and her new classmates Rei, Momiji, and Kouichi, Keito slowly finds the courage to open up to others and to accept their support. Will Keito return to acting? Will she find true friends? Love?

From Entropy:

Jin Young is a good student with good grades, but she has a little bit of an unstable mind. Hye Jung is a cheerful girl who helps out at her mom's "snack shop", a sort of small restaurant that offers light meals to diners. Both attended the same school, and both transferred to an independent-study private school, where they meet Si Hyung who is an instructor there. Si Hyung used to live in the same neighborhood with Jin Young when they were young, but he's surprised how Jin Young has changed into a cold person.