After overcoming various tumultuous events, mercenary sergeant Sousuke Sagara of Mithril and Whispered school girl Kaname Chidori return to their normal high school lives. Sousuke continues his efforts to assimilate with the civilian population and manage his mission at the same time, while Kaname attempts to support his endeavors (even though his antics often drive her up a wall). However, as their lives calm, new problems begin to appear. The appearance of an independent terrorist organization known as Amalgam and internal conflicts within Mithril threaten to wreak unity into a series of failures and betrayals. And new, powerful Arm Slave models only worsen the situation when the world's peace is at stake. As Kaname and Sousuke face their own inner battles amidst life-threatening fights, will they be able to make the right choices and change their future?

On her day off, Tessa wakes up in her commander chair. After regaining her composure, she notices that her favorite stuffed animal is missing and thus tries to remember what actually transpired the night before. To do so, she will spend time with all the main characters of the Danaan crew, and eventually recalls the events of the previous night.

Takuma Hirose is a blind young male high school student, though the cause for his blindness is undetermined. In order to heal his medical condition, he is sent to live in a village with his uncle. There, he meets several girls, three of which stand out more than any of the others. They are Hayami Kohinata, Hinata Kangura, and Otoha. Otoha temporarily heals his blindness and Hirose uses his sight to help others. He finds out that, for some reason, Hayami Kohinata is hated in the village, and he tries his best to help her out. Meanwhile, many sad secrets unfold in the village...

Lucky☆Star follows the daily lives of four cute high school girls—Konata Izumi, the lazy otaku; the Hiiragi twins, Tsukasa and Kagami (sugar and spice, respectively); and the smart and well-mannered Miyuki Takara. As they go about their lives at school and beyond, they develop their eccentric and lively friendship and making humorous observations about the world around them. Be it Japanese tradition, the intricacies of otaku culture, academics, or the correct way of preparing and eating various foods—no subject is safe from their musings.