While taking a ferry to Fuuka Academy, new students Mai Tokiha and her sickly younger brother, Takumi, spot a girl adrift on the water. Shortly after bringing her aboard, the ferry comes under attack from an assailant who summons a mechanical monster. Despite still recovering from her injuries, Mikoto Minagi fends off the monster using a supernatural sword. Mai soon discovers that Mikoto is a fellow Fuuka Academy student with abilities called HiME (Highly-advanced Materializing Equipment). Female students with HiME are responsible for defending the academy and the local city from the monstrous Orphans. After several incidents at the school involving battles against these mysterious creatures, Mai learns that she is a HiME herself and is capable of summoning a Child, a mechanical creature capable of great utility and firepower. Now burdened with new responsibilities, Mai joins 12 other HiME as they safeguard the school from a threat they know little about all while protecting the ones closest to them.

Every day, a young girl wearing a mask stands by the beach and sings a nostalgic melody. After experiencing two sudden heart-wrenching partings when she was only a child, Nino Arisugawa has been singing her songs to the ocean, bound by a promise made with her two childhood friends—her first love, Momo Sakaki, and a boy who composed music, Kanade Yuzu Yuzuriha. Having never met each other, the boys both individually promised that if Nino was ever separated from them, her voice would be the beacon to reunite them once again. After six long years, destiny has finally placed Nino, Momo, and Yuzu in the same high school. However, the passage of time has changed many things in their lives—while Nino relentlessly attempts to fulfill her childhood promise with the boys, Yuzu's feelings for her from the past resurface, and Momo goes to great lengths to prevent a reunion with Nino. Through music, will they be able to mend their friendship and overcome all the feelings involved in this complicated love triangle?

Maiku Kamishiro's past has always been somewhat of a mystery to him. The only clue he has to who his family might be is an old photograph showing two young children, a boy and a girl, playing in a small pool outside of a blue house. In an attempt to find his family, he moves to this blue house and begins working as a programmer. He's living a comfortable life until the day two very different girls show up at his door, both in possession of the same photograph, and both claiming to be his twin. With no way to prove who is a relative and who is a stranger, Maiku allows both girls to move in with him until they know for sure. (Source: ANN)

After regaining her squid-like abilities, Ika Musume plans to resume her self-appointed mission to destroy all of humanity. However, her carefree job as a waitress in the Lemon beach house meant she cannot help but laze around during her spare time! On top of that, she is saddled with many problems, such as being pursued by a group of alien-obsessed individuals and catching the interest of a crazy girl. Picking up after the conclusion of the first season, Shinryaku!? Ika Musume follows the hilarious life of Ika Musume as she plots her next invasion of the surface world.