Blue Drop (ブルー ドロップ, Burū Doroppu) is a Japanese science fiction yuri manga created by Akihito Yoshitomi.

The first DVD release on December 26, 2007, was accompanied with a bonus 6-chapter manga volume called Maiorita Tenshi (〜舞い降りた天使〜, Descended Angel).

The second, released on June 27, was titled Traitor Side, and included the fourth and final chapter of the Itazura one-shot series.

All the Blue Drop stories revolve around a war between humanity and the Arume (アルメ),[1] an alien race consisting solely of women.

All of them have blue eyes and their blood turns milky white when it touches air,[7] but their main characteristic lies in their gender:[5] they are all female, and their sexual orientation is homosexual.

[5] The aliens' sexual behaviour is dealt with even more prominently (and explicitly) in the Blue Drop: Tenshi no Bokura manga, which shows its consequences upon the human social structure.

[8] Unlike both manga stories, the Blue Drop: Tenshitachi no Gikyoku anime series is set before the war.

[2] Mari's background hides a traumatic past: five years before her arrival at Kaihō, all the inhabitants of the island where she lived died in one night.

Although most of the chapters in the original Blue Drop manga are auto-conclusive, the first recurrent character and main protagonist is Yui,[10] an alien/human hybrid introduced as a member of the resistance.

[5] Because of her alien heritage, Yui possesses their characteristic blue eyes, the white-colored blood, and their sexual orientation.

[1] The main characters in the Blue Drop: Tenshitachi no Gikyoku anime are Mari Wakatake (若竹 マリ, Wakatake Mari), voiced by Akiko Yajima (Japanese) and Hilary Haag (English), and Hagino Senkōji (千光寺 萩乃, Senkōji Hagino), voiced by Miyuki Sawashiro (Japanese) and Monica Rial (English).

[9] Written and illustrated by Akihito Yoshitomi, the original Blue Drop manga was serialized in the Japanese shōnen magazine Dengeki Comic Gao!, published by MediaWorks.

The first part was later included as a special chapter in the first volume of Blue Drop: Tenshi no Bokura, which was released on September 20, 2007.

[17] It focused on the original manga's storyline and featured Kaori Nazuka as Yui, Mami Kosuge as Misato, and Ryoko Nagata as Shōko.

[25] Theron Martin of Anime News Network argued that the series resembled Darker than Black with its "common gimmicks and story elements" like lesbian love, a play, and lost memory.

Even so, he argued that the show succeeds because it is "more about the characters than the gimmicks," is a "low-key series" and called it a "nearly-overlooked gem of a story" which will not have as big of an audience as it should have.