Dystopian (Post-)Apocalyptic Futuristic

[From AQUA Scans]
«✾✾» Japan, Year 2X65, Tokyo. As the population continues to drop due to a mysterious disease, through a certain incident, the fates of two young men, the orphan Noel, and Rikka, the heir of a distinguished Mafia family, will cross... A thriller, depicting the tale of their Bond of Blood...

[From MangaHelpers]
Scientists predicted an imminent meteor impact on Earth that would annihilate civilization, but contrary to their prediction, the meteor missed Earth. Though avoiding immediate destruction, humanity found that the meteor left behind something in its wake, something that would change the course of civilization forever: a new form of bacteria that ate through all known metals.
Facing this new era where all metals turn to ash, Jinkichi and his classmates will have to survive

Based on Nitro+CHiRAL's Japanese BL visual novel "Togainu no Chi"
This version, by Yamamoto Kana (2005), is said to cleanly (no overt BL) follow the Keisuke storyline.
1 Volume (Complete) - Raw: https://www.177mh.net/colist_170358.html
Alternate Story: Togainu no Chi, version by Chayamachi Suguro (2006) http://www.mangago.me/read-manga/togainu_no_chi/
Anime: http://kissanime.ru/Anime/Togainu-no-Chi

Based on Nitro+CHiRAL's Japanese BL visual novel "Togainu no Chi" - Version by Chayamachi Suguro (2006)
10 Volumes (On hiatus) - Raw: https://www.177mh.net/colist_170360.html
Alternate Story: Togainu no Chi, version by Yamamoto Kana (2005) http://www.mangago.me/read-manga/togainu_no_chi_zero/
Anime: http://kissanime.ru/Anime/Togainu-no-Chi

Note: The initial chapters uploaded here are all DJ // The actual story begins at "Vol.4 Ch.16-20", so it seems vol. 1-3 are missing...

Based off Nitro+CHiRAL's “Brain Crash Story” game of the same name. The story takes place many years in the future where the game "Rhyme", a virtual fighting game, is incredibly popular and people posses "All Mates", convenient AI computers. Aoba leads an ordinary life, working at a junk shop and living with his grandmother on the Island of Midori Jima. Unlike his friends, he doesn't participate in Rhyme, nor does he belong in a gang. However, when rumors of people disappearing spread, Aoba find

BL Anthology - Tragic stories of those for whom it is decided that they "Will Die Tomorrow"
Ch. 4 Sekai no Owari no Koi no Hajimari by Otono Awo - At the End of the World, a Love Begins: simply beautiful!! I loved this! I loved the setting, the idea the author chose to express the concept of "Will Die Tomorrow"...this was cool and emotional! Thinking about the circumstances in which Michiru met Saiki-san, how could happen that a total stranger helped him in that world...

[Baka-Updates] Our protagonist, Shakudou Takeru wakes up in a pile of debris. Before him, is a Tokyo completely unknown to him, ruled by people clothed in military uniforms...

His romance of 500 years: a masterpiece by Yamanaka Hiko. A beautiful story, a rare gem with unique plot

Torao attempted suicide after his lover Hikaru died but, after 250 years of suspended animation, he wakes up and finds an android meant to be his lover's substitute, but he is not really like him. "I'm sorry I don't bear much resemblance - I love you." awww my heart! Such a beautiful love between a human and an android. (complete comment at the page)

The actual novel can be read/downloaded from here:
http://www.ainokusabi.net/
http://www.yaoiotaku.com/forums/threads/14638-ai-no-kusabi-novel-by-yoshihara-reiko-eng
http://www.yaoiotaku.com/forums/threads/14638-ai-no-kusabi-novel-by-yoshihara-reiko-eng/page4

ova (2)
+ Ai no Kusabi 2012: ova (4)
https://kissanime.to/Anime/Ai-no-Kusabi
https://kissanime.to/Anime/Ai-no-Kusabi-2012

[Baka-Updates] A sci-fi story about peep rooms, digital angels and a group of mysterious guys called "Serene". Nozomi earns money though street fights, but one day, he meets a stronger guy and loses. He becomes the slave of the mysterious guy and has to work in a peep room.

Main Story: Aoi Hitsuji no Yume