If you're looking for manga similar to Neo Yokio: Pink Christmas, you might like these titles.
Nozomu Itoshiki is a high school teacher who views everything in life in the most negative way possible. Even his name reflects his personality: if the Japanese characters are written horizontally, they spell out 'despair.' One day during one of Nozomu's many suicide attempts an incredibly optimistic young girl named Kafka Fura rushes to save him from hanging on a sakura tree. Nozumu later finds out that Kafka is a student in his new class! In fact Nozomu's new class seems to be made up entirely of strange, troubled individuals who constantly foil his attempts to end his life.
Junichiro Koizumi: Prime Minister of Japan, or God of Mahjong incarnate? Watch him clash with other world titans such as George W. Bush, Kim Jong Il, and Vladimir Putin in the one force that matters in the political world: mahjong.
Three friends, Kotori, Yuuto, and Rin are trapped in school when the principle halfheartedly summons a horde of demons. The demons make a pact with each student in exchange for possessing them. Most of the students wished to be be good looking or to have longer legs, but Yuuto manages to stave off the possessed student body while Rin overpowers the weak demon possessing her. Yuuto makes a pact with a demon to return the school to normal, but what will happen to the school now that each student is being possessed by a demon?
The year is 1897, the era of the Wild West. Doctor Mordrid may be the scientific community’s outcast, but his unique skills as an archaeologist specializing in occult cases are second to none and begrudgingly recognized by most. With his trusty animal sidekick Kim and more than a few (mechanized) tricks up his sleeve, Doctor Mordrid sets forth to investigate incredible happenings on the American Frontier.
It's 16 years after the "Law for Public Order and Morals in Healthy Child-Raising" banned coarse language in the country. Tanukichi Okuma enrolls in the country's leading elite public morals school and is soon invited into the Anti-Societal Organization (SOX) by its founder, Ayame Kajou. As a member blackmailed into joining by Ayame, Tanukichi ends up taking part in obscene acts of terrorism against the talented student council president and his crush Anna.
Creating the world was a big job, but God finds that actually running it is a lot more work. Dealing with heaven, earth, and everything in between can make it hard for him to kick back and have a drink. Fortunately, he has Jesus and his right-hand man Gabe to keep things going in heaven and deal with the fallout of their Lord's many mishaps. Meanwhile, Lucifer and his assistant Ebag find that running hell is equally challenging. All the deceased sinners (and cats) of the world have been dumped in their laps, little girls keep summoning the devil to grant their wishes, and God keeps sending gay people to hell in a matchmaking attempt to find Lucifer the perfect man!
Shouta Yamakawa is in love with manga…and the 2-D girls in it! So when a casually uttered wish to have the lovely, frail Sora Nagihara-his favorite comic heroine-by his side comes true, Shouta can’t believe his eyes! But he quickly learns that while this Sora is just as cute as the one in his comic books, “frail” is the last word that comes to mind for her personality! She’s one bold, brutal babe, and she’s ready to bring the world to its knees for him, her new master?!
A girl shouts "penis" while running through the train station. In that instant, I fall flat on my face. After the enactment of the Public Morality and Wholesome Upbringing Law sixteen years ago, all sexual words have been lost in Japan. Okuma Tanukichi has entered one of the few schools with excellent public morals where his beloved upperclassman Anna serves as student council president. However, an obscene terrorist going by the name Blue Snowfield blackmails him into joining SOX, an obscene terrorist organization! Is this a prison or is it a harem?