This is a reboot of the original manga adaptation and will go down a different route, it starts right at the beginning of the original.

From Aerandria Scans: Souta, who's attending a confectionary school, is in a relationship with Saeko, a girl one year older than him. He fell in love at first sight with her four years ago, and right before Christmas last year, they finally had their first kiss. Because his girlfriend really loves chocolate, every day, Souta tries to polish his chocolate-making skills. Even when his girlfriend smells like cigarettes although she doesn't smoke, even when she turns down his invitation to a date on Valentine's day, he's still not broken-hearted at all, and he still continues to love her... Nominated for the 4th Manga Taisho Awards (2011).

Kyouichi is now divorced from his wife and carrying on a tenuous, homosexual relationship with Imagase. He has even become accustomed to having sex with Imagase every day. However, when Tamaki, a young coworker with a crush on Kyouichi, appears on the scene, it might be the beginning of the end for Kyouichi and Imagase. (Prequel) Kyuuso Ha Cheese no Yume Omiru

From Tokyopop: It's senior year, and Rica is seriously stressed out. She's got more homework, exams, and papers than she can handle, and was recently dumped by her boyfriend. In other words: Life sucks! One day, she's chatting online when she meets three classmates who hate school as much as she does. Together, they hatch a plan to blow up the school when no one is present. The countdown is on for X-Day ... Featured in this manga is a side story called The Last Supper.

From Beautiful-Soup: "1999" is an angsty and widely varied series about a bunch of teenagers. One of them is the son of a drug lord and so as you can imagine, all sorts of shit goes down, surrounded by a backdrop of convoluted and fluctuating interpersonal relationships. This a plot heavy manga with some mildly-explicit sexual activity.

"Sensei, is this a boy or a girl?" "Do you want to know?" Ichijo Mashiro and fellow classmates are enlisted in a mysterious weekly class that takes the form of a shared nightmare. Like most teenagers, Mashiro has a secret.. he's neither fully male nor female! So far, Mashiro's been able to live life as a boy, but all this changes when he's informed of a new class he 'must' partake in order to graduate from his elite preparatory school. To pass, he must find the key and the one way to find it is to enter into a nightmare world, where his body and soul are put at the mercy of the worst kind of enemies -- other school students, who are battling to find the key. From renowned author Mizushiro Setona, comes a riveting epic mystery that lies between the students, that will have you engrossed from one page to the next. Happiness, sadness, blood and tears will all be shown, but which one leads to an ending? Take the next step into the world of After School Nightmare! From Go! Comi: Like most teenagers, Mashiro Ichijo has a secret. But Mashiro’s secret is that he’s neither fully male nor female! So far, Mashiro’s been able to live his life as a boy, but all this changes when he’s informed of a new class he must take in order to graduate from his elite prep school. To pass, he must find the “Key”…and the only way to find it is to enter into a nightmare world where his body and soul are put at the mercy of the worst kind of enemies: his classmates!

From Asian Girls on Mopeds: Sakurai Ichiko is a 29-year-old woman whose head contains council members (each with differing personalities) that dictate her every thought and decision. While waiting at the train station one day, she encounters Saotome, a man whom she met and made short conversation with at a drinking party with friends. Although she’s interested in him, being a much a older woman, Ichiko hesitates over whether or not she should approach him, causing a wave of uproar between her intracranial council members.

From ShoujoMagic: 1) Futari no Tame ni Sekai wa Aru no (2 chapters and an extra) Asukagawa Chiharu is student body president of Ushitora High. Kisaragi Kyou is student body president of Ushitora's rival school, Bishin Academy. That naturally makes Chiharu and Kyou bitter rivals as well, but the relationship they hesitate to flaunt in front of the public eye is one of... lovers! They even have sex at hotels and are an average (!?) couple!! See "Soko wa Nemuri no Mori," story 02 : "The Star Knows Everything", for a side story of this manga. 2) Valentine Cinema 3) The Queen's Favorite

The young tenor singer Dimitri miraculously escaped with his life after a severe accident. But soon after that, strange cases of group-suicides started to happen all around him… A vampire tale of love and survival!

From ShoujoMagic: A collection of short shounen-ai stories by Mizushiro Setona, all connected by the theme of plantlife. [STORY 01] (English Title) Breakfast (Japanese Title) ブレックファスト (Romaji Title) Burekkufasuto The tale of a boy who displays the symptoms of man-eating syndrome. [STORY 02] (English Title) The Tale of the Ring (Japanese Title) 指輪物語 (Romaji Title) Yubiwa Monogatari The tale of two boys who are dating each other and mutually hiding the fact that both are dating their teacher, who frets because a ring has been lost. [STORY 03] (Japanese Title) Honey β The tale of a flower that blooms by inhaling memories. But even if our memories are taken from us, some precious things are never forgotten. "I don't fear losing my memory if I can feel this way again tomorrow..." [STORY 04] (English Title) Undying Illness (Japanese Title) フジノヤマイ (Romaji Title) Fuji no Yamai See "Mister Mermaid," story 2. [STORY 05] (English Title) Aconite (Japanese Title) トリカブト (Romaji Title) Torikabuto dropped by ShoujoMagic on 10-15-07

Hatsune is a male prostitute living during the Shouwa era in Edo. Suzuro is one of Hatsune's regular, but he only wants to paint Hatsune and leaves after he does. Hatsune would talk about this family with Suzuro and revealed that his brother was his lover. As if by fate, Suzuro who began to realize his feelings for Hatsune, coincidentally met with Hatsune's brother...

From ShoujoMagic: Story 1: Automatic Angel Serika, a high-school student, is known for being a well rounded girl with an attractive face and figure. She is clear-headed and has a talent for sports. But she's an... android!? Vol. 2, Story 2: The Winter Was Trying to End Tale of a high school professor and student.

MISTER MERMAID: On a full moon night, Subaru - a merman - coincidentally saved a man who sank into the ocean. After that, in order to see that man again, Subaru traded off his tail for a pair of legs and came to the surface to find Tatsuki - the man's name. Despite of his throbbing feet and his lost voice, Subaru was happy to be able to stay by Tatsuki's side. However, his happiness soon faded away when he found out the reason why Tatsuki was at the bottom of the ocean that day. FUJI NO YAMAI (side story): Byakuya had an incurable undying illness, which means he couldn't die. Gin, his best friend, made a promise that he would take care of Byakuya until death and the promise had been kept for 16 generations. However, Gin the Sixteenth had no intention of making babies for the next generation; instead, he kept his promise with Byakuya in a way that none of the previous Gins had done.

Kyouichi's indecisive character has led him to repeatedly commit the foolish mistake of adultury. One day, Imagase, a college classmate he hasn't seen since graduation, shows up as the private detective hired by his wife to investigate his infidelity. Imagase, however, proposes a deal. He won't tell Kyouichi's wife about his affairs, but, for compensation, he makes an unbelievable demand: "I want your body in exchange..." An adult love story about two men and agonizing longing... by PresenceDear (sequel) Sojou no Koi wa Nido Haneru

From Go! Comi:Like most teenagers, Mashiro Ichijo has a secret. But Mashiro's secret is that he’s neither fully male nor female! So far, Mashiro's been able to live his life as a boy, but all this changes when he's informed of a new class he must take in order to graduate from his elite prep school. To pass, he must find the “Key”…and the only way to find it is to enter into a nightmare world where his body and soul are put at the mercy of the worst kind of enemies: his classmates!

The first person who hurt me was of my own gender. Tsubaki is in the same class as Kaoru and Koutarou is the gentle big brother. What embrace their souls are desires and tenacity... They are hurt, they throb, they are drowned, they cry... They love with their body and soul, these are the real ordinary lives of these boys. (Note: the title for this manga (Dousei Ai) generally means "homosexuality", however, the kanji used has a different meaning than the kanji that are properly used for spelling "homosexuality". The kanji for this series is the same for "living together" (同棲) instead of (同性) which means "same-sex")