Osamu and Youko Sonoyama want more than anything to adopt every child from Soramame House, but the wealthy couple can only pick one due to their increasingly old age. While they contemplate this delicate decision, one child's alluring beauty and gentle soul instantly draw them in. Two months later, the Sonoyamas welcome 13-year-old Hitori into their warm and loving home. However, Hitori's humble and overly polite exterior is merely a masquerade. In reality, Hitori is a carefully crafted character played by identical twins Migi and Dali. For them, being the ideal child of this kind couple is merely a stepping stone to infiltrating a certain quiet town. While dutifully protecting their cover, the twins work toward their true objective: to discover the truth behind a past incident that left them with a burning desire for vengeance.

The time of destruction is coming ever closer without a doubt. It cannot be stopped. To know death, to gaze at death, to face death. Makoto and his allies have grown through the many meetings and partings they have experienced. Their fight might not be for the sake of the world, but for themselves. Even so, they have continued to fight, believing that there are peaceful days waiting at the end of the battle. However, a boy says that destruction is the fate that humanity must shoulder. The boy they believed to be their friend tells them the truth of the situation without an emotion on his face. The season changes to winter. Makoto makes a decision in order to greet the spring that is waiting beyond... (Source: ANN)

Generations have passed since the war with the Space Monsters started, and none remain who know how it began, with even records of those times being scarce. It is a lost cause, but humanity still fights against them, relying on the Topless: a group of elite space pilots with special powers that allow them to use the Buster Machines—the last hope against the Space Monsters. Nono, a girl from a remote Martian town, has heard tales all her life of the legendary pilot Nono-Riri, and wants nothing more than to leave her humble life behind and follow in the footsteps of her idol. Though she has no idea of the dangers that lie ahead, nothing will stop her from achieving her dream. While Nono is down on her luck, she chances upon the lonesome Topless pilot Lal'C Melk Mark, and decides to stake her entire future on following Lal'C, no matter the cost.

After losing his entire family in a car crash, Taiyou Asano tries to pull away from his childhood friend, Mutsumi Yozakura, but she assures him she is not going anywhere. Nevertheless, Taiyou becomes socially awkward, struggling to make friends at school despite the efforts of his persistent classmates. One day, the vice principal calls Taiyou to his office, only to begin threatening the boy's life. Taiyou is swept away by a stranger and eventually awakens to Mutsumi, who introduces him to her siblings—a family of spies who harbor superhuman abilities. Every generation produces one ordinary human who becomes the family head. Mutsumi is one of these, and the family's mission is to protect her with their lives. The vice principal's real name is Kyoichiro Yozakura, and he is the eldest son of the family. As Kyouichiro believes that Taiyou is a threat to Mutsumi's life, the only way to keep both Taiyou and Mutsumi safe is for them to get married; the family has a rule that prevents them from killing within the Yozakura household. Though at first reluctant, Taiyou agrees in order to protect Mutsumi. Now he must train as a Yozakura spy to ward off the constant threats on the lives of both Mutsumi and himself.