One day, Kei Kusanagi notices a strange glowing woman by the lake. He discovers that the woman is actually an alien officer from the Galaxy Federation named Mizuho Kazami, and even more shocking—she's also his teacher! In spite of this setback, he and his teacher gradually get to know each other and a romance blossoms between them. However, soon enough, the principal of the school finds out about their relationship. The solution? Get married! Together, the newlyweds must keep their marriage a secret, not only from Kei's high school friends, but also the Galaxy Federation. Onegai☆Teacher is the fragile but comedic love story of an alien and her student.

Narumi Fujishima may seem like a normal high school student at first glance, but in reality he is a pessimistic outsider. Due to his father's work, he had to constantly transfer schools, and thus he has never managed to become a part of society. When he is forced to join the gardening club by his cheerful classmate Ayaka Shinozaki, Narumi encounters the genius hacker Alice, who lives in isolation above Hanamaru, the ramen shop where Ayaka works part-time. He then discovers that Alice is running a special private detective agency, and that all her professional associates refer to themselves as NEETs: Not in Education, Employment, or Training. Joining the NEET detective agency due to his personal connection with a criminal case, Narumi finds himself entangled in a world of dangerous investigations conducted by the ill-assorted group of detectives, all the while trying to track down the crime syndicate which seems to have mysterious ties to Alice.

Tooru Kirishima's notoriety is spread far and wide in the underworld. He is most commonly known as The Demon of Sakuragi—a man who is not afraid to resort to violence if deemed necessary. After almost jeopardizing a peace treaty, his boss tasks him with the most difficult job he has ever had: taking care of seven-year-old Yaeka Sakuragi—the boss' precious daughter—so that Tooru understands what it means to be responsible for another life. At first, the two do not seem to meet eye to eye, as Tooru has no clue on how to communicate with Yaeka, and the young girl is not used to expressing her emotions. However, as time goes on, they come to understand each other despite their differences. The fearsome right-hand man of a yakuza boss and the child he must protect are about to learn that family is not always bound by blood.

Yotarou is a former yakuza member fresh out of prison and fixated on just one thing: rather than return to a life of crime, the young man aspires to take to the stage of rakugo, a traditional Japanese form of comedic storytelling. Inspired during his incarceration by the performance of distinguished practitioner Yakumo Yuurakutei, he sets his mind on meeting the man who changed his life. After hearing Yotarou's desperate appeal for his mentorship, Yakumo is left with no choice but to accept his very first apprentice. As he eagerly begins his training, Yotarou meets Konatsu, an abrasive young woman who has been under Yakumo's care ever since her beloved father Sukeroku Yuurakutei, another prolific rakugo performer, passed away. Through her hidden passion, Yotarou is drawn to Sukeroku's unique style of rakugo despite learning under contrasting techniques. Upon seeing this, old memories and feelings return to Yakumo who reminisces about a much earlier time when he made a promise with his greatest rival. Shouwa Genroku Rakugo Shinjuu is a story set in both the past and present, depicting the art of rakugo, the relationships it creates, and the lives and hearts of those dedicated to keeping the unique form of storytelling alive.