Aspiring light novel author Yuu Nagami regularly enters writing competitions but has yet to win a single one. Despite his recurring failures, he remains steadfast in his resolve to become a better writer. When he takes a look at the list of winning authors in the latest contest he joined, he notices that someone named Chikai Towano dominated the competition. He soon discovers that behind the pen name is his sister Suzuka—the last person he can imagine being an author. Suzuka cannot reveal to anyone that she is Chikai Towano and requests her brother to take her place. Yuu agrees with one condition: he will continue posing as Chikai Towano for his sister until he publishes his own book. Until that happens, Yuu uses his new identity as an opportunity to improve his writing skills and meet fellow authors and new acquaintances along the way. [Written by MAL Rewrite]

Struggling yet brilliant teenager Minato Sahashi has failed his college entrance exams for the second time, resulting in him being regarded as worthless by those around him. However, the course of his seemingly bleak future is altered dramatically when a beautiful, supernatural woman falls from the sky and into his life. That woman, Musubi, is a unique being known as a "Sekirei," a humanoid extraterrestrial with extraordinary abilities. These aliens are known for kissing humans carrying the Ashikabi gene in order to awaken additional latent powers deep within. Recognizing the potential within the seemingly insignificant youth, Musubi kisses the bewildered Minato, initiating a bond between the two of them. This drags him into the high-stakes world of the Sekirei, where he and his new partner must compete against others in a battle for survival called the "Sekirei Plan." However, unbeknownst to the contestants, there is far more at risk that what the competition initially entailed. [Written by MAL Rewrite]

The second stage of the battle royale known as the Sekirei Plan is underway. Shintou Teito has been closed off; no Sekirei or Ashikabi may leave. Minato Sahashi and his harem of Sekirei must now prepare to fight new battles as changes to the rules are put into place. However, not all groups will return to the battle: some Sekirei are loved very much by their Ashikabi partners, who would rather forfeit the prize than see them perish. In the midst of the action, someone close to Minato may be more involved than he had ever imagined, and threats lurk around every corner. There are even rumors that the "Single Numbers," the most powerful type of Sekirei, have entered the fray. In the eyes of the "Game Master" Minaka Hiroto, everything is proceeding according to plan. [Written by MAL Rewrite]