After taking one hundred secret photos and observing him from afar for months, second-year high schooler Yuki Kurihara has finally mustered up the courage to ask out her first-year crush Shinya "Momo" Momotsuki. Although taken by surprise, the bashful Momo accepts; however, he does not know the profoundly abnormal truth. As her strait-laced friend, Norika Mizuyama, has observed, Yuki has developed some unnerving—but nonetheless sincere—habits: taking pictures of Momo in secret, doing extensive research into his personal life, collecting his used straws, and even going "Momo watching." Though Momo remains blissfully unaware of his new girlfriend's peculiar habits, he does notice some oddities in their daily conversations. Still unsure and nervous about his first relationship, Momo finds himself regularly getting into awkward interactions due to his inexperience, but nevertheless resolves to make his new girlfriend happy. Momokuri follows Yuki and Momo as they shyly explore their newfound love, and also deal with the problems that arise from it.

Nanba is the world's most formidable prison, built to incarcerate criminals who are too slippery to stay in ordinary confinement. The four inmates who occupy Cell 13 are particularly cunning on that behalf, having escaped every other prison with a perfect success rate. There is Juugo, a specialist in locks who has spent the majority of his life in prison; Uno, a gambler with great intuition; Nico, an otaku whose body reacts strangely to drugs; and Rock, a bruiser with a love for food. The daily shenanigans of the four prisoners always cause trouble for the building supervisor, Hajime Sugoroku, who desperately tries to prevent them from breaking out of Nanba. Nanbaka follows the comedic, sparkle-filled exploits of these prisoners and their guards. From three square meals a day to sports festivals, prison life in Nanba isn't actually that bad—and it is the closest these four have to a home.

The official website for the Nanbaka television anime announced that the "Nanfes" event in April will screen a previously unreleased anime special.

The second part of Nanbaka. The prisoners and their guards continue their comfortable lives at Nanba Prison. However, from the shadows emerges a new threat: Enki Gokuu, a person from Samon's past, who has mysterious goals of his own.