It began in 1945, at the end of the Pacific War. Alien invaders filled the earth's Skies, and mankind was forced to confront an unprecedented threat. For the first time in human history, people of all cultures came together under one banner. This war has now been raging for over fifty years. Countless lives have been lost, and the Japanese military is now forced to rely on young people such as Atsushi Hayami and his high school class, also known as Unit 5121. This new generation fearlessly struggles on with the aid of the HWT humanoid combat machines and the devastating PBE bomb. (Source: Media Blasters)

During his summer vacation, middle school student Nagasumi Michishio travels to the Seto Inland Sea. One day, while swimming at Mio Sun Beach, his leg suddenly cramps. No one is close enough to notice his desperate screams for help, and so he sinks into the ocean, where he is left to drown alone. Just as he loses consciousness, however, a mermaid appears and saves his life. That night, Nagasumi is visited by his savior, a girl who introduces herself as Sun Seto—a mermaid from a yakuza family. As it turns out, under mermaid law, a mermaid whose identity is revealed to a human must be punished by execution. To avoid this harrowing outcome, the Seto family propose a solution: Nagasumi must marry Sun or die at the hands of Gouzaburou, Sun's father and boss of the Seto clan. Faced with no other option, Nagasumi takes her hand in marriage. Now, the newlyweds face the difficult task of keeping their relationship secret. Between Gouzaburou's unending attempts on Nagasumi's life and the eccentric antics of a slew of antagonists, a genuine and innocent love blossoms between the pair as they adapt to their new life. [Written by MAL Rewrite]

The Society for the Study of Modern Visual Culture, otherwise known as Genshiken, is now under the charge of a more confident Sasahara. Things have changed in between semesters, and the otaku club now has a new otaku-hating member named Ogiue. Sasahara's initial goal of starting a doujin circle and selling those fan-made magazines at the next Comic Festival becomes a reality, but reality is a cruel master... who apparently crossplays. Afterward, the club is abuzz with talk about Tanaka and Ohno's relationship, which takes a hesitant step forward. (Source: Media Blasters)

Mao Onigawara is a happy 8-year-old grade-schooler and the granddaughter of Chief of Staff of Ground Defense Force. Equipped with her cloverleaf-shaped badge which enables her to transform (but gives her no special power whatsoever), Mao and her best friends (granddaughters of Chief of Staff of Air and Marine Defense Force, respectively) will defend Japan against the invasion from "cute aliens," who are way too cute to be dealt with by regular armed forces. (Source: ANN)