From Fantasyshrine:

1-3) Nosocomial Infection & Informed Consent
A brilliant surgeon originally from a university hospital, Sawamura Iori, and a married physician, Yagi Tomoya are having an infamous affair!! They conduct their taboo affair in a hospital room where a comatose boy has been lying for the past 5 years. One night, Tomoya was rushed to the ER due to a car accident... Is it really an accident or a suicide attempt…? Can Iori save his lover…? Suddenly the comatose boy miraculously awakens… This story intertwines all three men and their struggles for a new beginning… (Continued in Shujii)

4-6) I Can't Pray for Your Happiness & I Have.
A wannabe pilot meets a beautiful young man who has lingering feelings for his ex-boyfriend.

Extra: Residence.
Sou, the coma patient from the main story, finds a new start at love.

Otoji is searching for his older brother in seedy, urban Yokosuka. During this search he meets up with Joe, a fashionable prostitute who eventually joins him with his search. Along the way Joe aquaints him with the wonders of sex and prostitution, and the flexibility of being both seme and uke! But while Otoji deals with the search he and Joe face the darker side of their lifestyle.

Honami's the first boyfriend Shouji has ever had, but he knows that Honami had a "jerk-off buddy" named Terumi back in middle school. Terumi never went on to high school, instead dropping out to work in his parents' gas station, and since then he and Honami have lost contact. Though he tries to play it off, Shouji instantly realises that Terumi means a lot to his boyfriend.

Determined to make the acquaintance of the guy Honami's so enamoured of, Shouji pretends he wants to join up with Terumi's biker gang. But as they spend time together, the curiosity and rivalry between them begins to evolve into something else entirely...

Ryu is sleeping with his college professor, but doesn't feel loved, so he decides to kidnap his professor's son, Hayato, out of revenge. As it turns out, Hayato's relationship with his father is not very good, so he winds up living with Ryu.

The doujinshi called "Nezi no Kaiten - EX", (done by the mangaka) begins when they start living together. It was released inside the book -6mm no Taboo.

Ace, a human teenager, has been raised by King and Jay, vampires who have lived an eternal lifetime. As he grows up, he became attracted to Jay and Jay also comes to yearn strongly for Ace's blood. King and Jay, afraid that their secret will be exposed, decide to send Ace away to a boarding school. But when Ace finds that out, he wishes to be a vampire like them.
Sadahiro Mika's Gothic love story about the growth of a teenager who's raised up by vampires and the feeling of a vampire who live in eternal life.

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Also two additional oneshots:
1) Pathos dj - Deep Throat (beware, this is also the name of the extra at the end of volume 1 of Pathos, but it's two different releases);
2) Pathos dj - EX.

Taiki agrees to see his college friends Ruma and Hoshioka to celebrate their wedding. But during dinner, Hoshioka is shot and Ruma loses his memory. Why was she killed? And will Ruma ever remember what happened?

Three friends re-unite after not seeing each other after college. The occasion is the wedding between the two. However, on this fateful day, the newly-wed woman was shot, and consequently died. The newly-wed man, because of the shock, loses his memories of the woman and his marriage to her, among other things. However, he remembers his best friend (the other guy with them), and that best friend helps him to put his life together again and discover the truth behind the death of his wife.

From Fantasyshrine:

1-3) Physician In Charge
Due to an accident, which caused his memory loss, Tomoya doesn't remember his family nor his lover, Iori. However, it never changed Iori's love for Tomoya! As Tomoya's primary physician, Iori brought Tomoya to the U.S. for treatment, as well as a new start for their future together?

4-5) The Thorn In The Heart
Continues the story of Sou and Sugino.

Extra) Dr. Yagi's Clinical Records

From Fantasyshrine:

Ritsuro is an expert in surfing and sex but a novice in love. As fate would have it, he meets another novice in both love and surfing. On the Shonan* beach, these two novices actually fell in love... with each other... But will their love survive from all the confusion, hurt, and growing up? A legend of love among surfers!

(*Shonan: a leading resort area in central Japan famous for surfing, sail-boating, and water sports)

+ One-shot: Hold me Tight
Jinno is suffering from a stomach cancer and lost his will to live, His doctor revived him once, can he do it again?

Collection of oneshots:

1) 3 1/2
Three guys share an American Forces house, but one of them, a very conservative guy, cannot put up with the other two guys' profligate sex life...

2) Dessin
Two guys "break-up" & "get back together" repetitively just like a game. But one of the guys becomes unable to keep it up...

3) Torso
A student who indulges the masturbation with torso knows the sex with flesh-and-blood guy for the first time...

4) Sasayaka na Yokubou
A bullied homosexual student who has a taste for "peeping" adores two very cool guys who look kings in their school. The student saves them in exchange for observing their sex.

5) Metamorphosis
A guy who bears a load of debt by "seminar of self-development" tries prostitution and is broken in by a rich guy who seems to like to dominate in kinky sex, but what is this guy really after?

6) Vanilla Boys
A guy finds a lover at Shinjuku, a famous gay date spot for the first time by pretending he likes hard core sex but in reality he is more into gentle "vanilla" sex.

From Nakama:

Toma and Miyako were raised in the same orphanage. From the moment they met, Miyako has been unable to repress the impulse to soil Toma's beautiful hands. Sadistically embracing Tom is the proof of profoundly sweet love. What awaits the two who wound each other and lick each other's wounds!? The hard Eros of madness and pure love! The forefront of forbidden SM!

In the Under Grand Hotel (2013) series:

V.1 - Kiss & Kill
30 meters underground, a prison where escape is impossible; the United States penitentiary, The Underground Hotel. Only the people who enjoy living in this place, a life cut off from the sun, call it by another name: The Under Grand Hotel. Absorbed in pleasure-seeking sex, the shut-call, Erie (leader of the prisoners) isn't watching the men he's raping each night, but rather one man alone. Norman.

Norman, who keeps trying to harm himself as a result of trauma, the kind doctor who cares for him, Van, and Erie, who's falling into a brutal love that's more akin to hatred. What will happen when these various feelings are made to intertwine into a closed-off world? From storyteller Sadahiro Mika, the long-awaited, mature love story of the Under Grand Hotel begins!

V.2 - Last Dinner
Erie is send to level 4 of UGH and reunites with an old acquaintance.

Under Grand Hotel is the inmate's name for a prison in the US. Sen is a Japanese guy who has been imprisoned after killing his lover's husband. Sword Fish is the leader of the prison. Sen needs Sword's protection, but can a love story work in a prison?

From Nakama:

The person Aiba Misao loves is an onnagata in taishuu engeki, named Yumedono Ginnojou. He fell in love when he saw this person on stage, believing him to be a girl. Thus, when the plain Oosato Ginji is transferred to his school, he fails to recognize him as his much-admired Ginnojou. However, Ginnojou finds love, becomes even more enthralling and makes a big break in a commercial. A long-distance relationship, a frustrating love… Complications turn these two people into adults!

In addition to the title series, also included is a hard love story where East meets West on the streets of New York!

From Nakama:

Toma and Miyako, who are living life on the run, and Itsuki, a wealthy idler who shows abnormal interests. Is what lies beyond the abnormal sex unfolding day and night light or darkness...!? Love is a labyrinth, the other side of which is desire polluted with blood and semen. The concluding volume of Mika Sadahiro's full-spirited SM love that will change the world!!

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…

Collection of oneshots:

1) Half Moon
Tsukito is known as the "Angel of Death" due to the misfortune that falls to anyone that associates with him. A yakuza intrusted with the mission to kill a trader, is looking for a one sweet night before the deadly mission. But perhaps the night will become more than just one night. "remember me in night of the half moon"

2) Private Gallery
What is fake and what is real - in art and love?

3) Lover's Return
Akimi Kenishi was kidnapped as a little boy in a foreign country and became a pedophiles toy in human trafficking business. His parents hired a detective to rescue their son. And the boy falls in love with his hero.

4) Night of Dismantlement
Kou was 12 when he was violated by his older brother. But the one who feels the passion is Kou, and he fears that one day, his aniki will leave him. The insecurity lead him to the wrong path. Will his brother make Kou his own?

5) -6mm no Taboo

6) Neji no Kaiten EX
Continuation of Neji no Kaiten
Hyato is moving into Ryuu's apartment in the excuse of experiencing the real world. What his parents don't know, is that they are actually lovers. But Ryuu is Hyato's first time, but Hyato isn't Ryuu's first time. But why is Ryuu so insistent in wearing condom? Does he plan to have other partners beside him?

WARNING: The third story "Lover's Return" contains Shota and S&M.
The fourth story "Night of Dismantlement" contains incest.

This manga contains a series of one-shots that feature Hanai Shishimaru, the perverted boss of ‘The Help-for-Help-Seekers Room’, which will do anything for their clients except murder. Causing divorces, turning someone gay, ‘relieving stress’ on a crowded train…… Just how far will he go?

The first, fourth and fifth one-shots, XI -Extreme Love-, Fool and Shadow Game, as well as the extra, La décadanse, are sequels to Buddy System.

A good-looking medical student named Goro, whose father is a famous professor, happens to be involved in a violent bandit Honjo who rapes women, uses modified guns and scares people to get their money. As Goro clearly understands Honjo's weak points, he turns out to become a huge threat to the ordinary life of the gangster.

After being deeply linked to an extremism project, Goro puts himself into many dangerous situations; however, Honjo always shows up for him. Untraditional chemistry between two tough guys who put their head over their heart whenever they're close to each other; somehow still want to possess the other.