The Akame ga Kill! manga and anime series features an extensive cast of fictional characters. The visuals of the characters were designed by Tetsuya Tashiro, while their stories were created by Takahiro. The story focuses on Tatsumi, a young warrior who joins an assassin group called Night Raid to fight corruption from the Empire. Its members, along with other characters in the series, wield super weapons called Teigu (帝具?, Anime: Imperial Arms).[ch. 5]
In 2007, Takahiro was asked to do a manga for Square Enix magazine. He originally came up with the idea of an "all-female band of assassins, and the protagonist is a boy who is captured by them and has to work for them." After his editor approved the idea, he waited on serialization until his company had stabilized and had released two other titles, during which he developed the characters, story and world. In August 2009, following the release of Majikoi - Oh! Samurai Girls, Takahiro looked for an artist for the serialization, and recruited Tashiro Tetsuya to do the illustrations. He liked Tashiro's ability to draw fast-paced action scenes and that he can draw cute girls.[vol. 1:postscript]
Takahiro has written additional background information and profiles about some of the characters in the postscripts of the volume compilations, such as for the Three Beasts[vol. 3:postscript] and the Jaegers.[vol. 4:postscript] The Danger Beasts (危険種 kikenshu?) were conceived to be any creature that attacks the humans in the world and are similar to monsters seen in role-playing games with different classifications from Class 4 to Class 1, and Special and Super Class designations at the top for the legendary beasts.[vol. 5:postscript]