Seigi, a martial arts trained middle schooler, often feels driven to protect the weaker people around him. One day, he defends a homeless man against some punks, and the man gives him a strange tattoo on his palm in return. The tattoo is a secret weapon produced in the arms race between America and the Serinistan Kingdom. Seigi finds himself in over his head when a powerful girl, using the same secret weapon, violently pursues him in order to retrieve it. His skill at martial arts may not be enough to keep him alive, but will he be able to learn how to trigger the power of his tattoo in time? (Source: MU)

Mafia is rife in America where assassinations are a regular occurrence on the streets. Inferno, a mysterious company, is behind most of these dealings through the use of their near-invincible human weapon, Phantom. One day, a Japanese tourist accidentally witnesses Phantom's latest murder. Desperate to escape, the tourist hides in a secluded building. However, Phantom, revealed to be a young woman named Ein, and the leader of Inferno Scythe Master captures the tourist and brainwashes him. Given the name Zwei, this once peaceful tourist is now a puppet of Inferno with no memories. Drawn into a world of lies, deceit, and violence, Zwei must fight to survive, hopefully to one day regain his memories and escape from this world where he is constantly on the brink of death.

They say that the more things change, the more they stay the same, and those words could not be more true for the student council of Ousai Private Academy. Though an entire year has passed—bringing the senior members to their final year of high school—not much has changed. President Shino Amakusa is just as perverted as ever, Secretary Aria Shichijou still refuses to put on a pair of panties, Treasurer Suzu Hagimura has yet to grow an inch, and Vice President Takatoshi Tsuda is still stuck as the straight man to their crazy antics. Of course, limiting the fun to a four-way might get a little stale; although the group still messes around with the Judo Club and the Newspaper Club, more girls have come to get in on the excitement. Takatoshi's sister Kotomi, a new student at Ousai, is as perverse as the president, while Uomi, the aloof student council president of the nearby Eiryou High School, fits right in with the insanity at Ousai. With loads of absurdity and sexual humor that keeps on coming, Takatoshi needs to harden up if he is going to keep up with all the madness around him.

Akira Tachibana, a reserved high school student and former track runner, has not been able to race the same as she used to since she experienced a severe foot injury. And although she is regarded as attractive by her classmates, she is not interested in the boys around school. While working part-time at the Garden Cafe, Akira begins to develop feelings for the manager—a 45-year-old man named Masami Kondou—despite the large age gap. Kondou shows genuine concern and kindness toward the customers of his restaurant, which, while viewed by others as soft or weak, draws Akira to him. Spending time together at the restaurant, they grow closer, which only strengthens her feelings. Weighed down by these uncertain emotions, Akira finally resolves to confess, but what will be the result?