Not everyone wishes for a peaceful afterlife… least of all Bonzo Scalobania, whose dearest wish is to find a case for a skeleton detective like him to solve! Along with his unreliable assistant, Vampy Vinegret, and zombie frenemy/bounty hunter Nero Lichman, Bonzo swears to solve the problems of Limbo City! But does it still count if the problems he’s solving are ones of his and his friends’ own making?? A wacky, weird, heartwarming tale for the undead in us all. (Source: Kodansha USA)

Jinichirou Taira, an unemployed 30-year-old, suddenly receives a letter telling him to fight against an unknown life form. He is now forced to accept this new job where he has to pilot a new mechanical armor called "RIZE." The name "RIZE" was used because they are the only ones that can hope to save humanity. At the frontline of the battlefield, he is now fated to save the world without anyone ever knowing...!? (Source: Shogakukan, translated)

Pre-Lunatics depicts the events occurring shortly before and at the very beginning of case#0:lunatics. It shows a glimpse into Ryo Kazan's mental breakdown following the events of Moonlight Syndrome, Sumio Kodai leaving HQ after getting a bad feeling, and Tetsugoro Kusabi looking at a picture of Toriko Kusabi and Christina. It leads directly into lunatics, with its last few pages matching the beginning of the case. (Source: Suda51 Wiki)

Lupin III spin-off about Kouichi Zenigata. *Note: Includes 2 extra chapters.*

Disowned, disgraced, and doomed to be a farmer. Being “blessed” with a farmer affinity is practically a death sentence for Chris Sparring. It’s nothing close to the sword-wielding class he’d been raised to inherit, that’s for sure. To make matters worse, his twin brother receives the affinity of a sword god instead, and wastes no time funneling years of jealousy into an attempt on Chris’s life. With nothing left to lose, Chris must find a way to make it on his own and avenge his name. And this “useless” poison resistance of his may be just what he needs to turn the tables! (Source: J-Novel Club)

Kasumi, a high school graduate who entered a dark-side company 3 years ago was in the midst of a late night overtime for the 30th day in a row when she wished that she could have "a single day off" to the shooting star she was watching on the roof when suddenly she was swallowed by a mysterious light...... The next thing she knew, she was standing, waiting to be introduced to her new colleagues at "White Products"! Will Kasumi be able to get used to the culture of the light side of the business after thinking that the dark side's dealings are "normal"? (Source: Kadokawa, translated) *Note: Includes three extra chapters.*

At the end of World War II, a demon-summoning ritual drastically altered the face of the earth. Now, a hundred years later, demons rule the world, and humanity fights back using magicite-powered armored mechs. In the year 2055, a boy named Keita Kawakami enrolls in Japan's military academy. Possessing memories of an alternate modern era, he successfully pilots a prototype mech that no one else has even been able to activate. When Keita is suddenly deployed to the battlefield, he uses the knowledge from his previous life to achieve results that defy all established norms. Thus begins humanity's battle to reclaim the world. (Source: Yen Press)

The Kingdom of Lienrhein welcomes a person with memories of another world as a saint and queen. According to this rule, Elys, who has the memory of a "rekijo" (a girl who likes history), becomes the queen, but she is married for political reasons and is forced to live a life where she does not feel the love of King Leenhardt. When Haruna, who has been teleported from another world, appears, Leenhardt's feelings for Haruna begin to grow. One day, when she finds out that the king has spent the night with Haruna, Elys finally makes up her mind, "I'm leaving this place!" (Source: Kodansha, translated)

The manga centers on 17-year-old protagonist Gekitetsu Amō, who does not stand out in school, but under the excuse of "eliminating harmful elements from the world" begins committing mass murder. Source: Anime News Network

Manga adaptation of the visual novel Tomoyo After: It's a Wonderful Life. Can be taken as what happens after the Tomoyo route from the Clannad game, with Tomoyo and Tomoya being a pair.

Little Busters!' story revolves around the main protagonist Riki Naoe, a young male high school student. When Riki was a child, his parents died, leaving him hopeless and depressed. What saved him was a group of his friends who referred to themselves as the Little Busters; they took Riki out and played together with him during his time of need. He really enjoyed playing with them, and his grief gradually faded away. When the story begins, they are in their second year of the high school they attend. They still hang out together, and enjoy their school life. (c) Wikipedia

The story centers on Tomoyo's arc from the Clannad visual novel.