Nagasumi's in hot water after a beautiful, young mermaid named Sun saves him from drowning. The deep-sea sweetheart's dad is a merman yakuza prone to executing anyone who learns his family's scaly secret! Luckily, there's a catch - if Nagasumi agrees to marry Sun, he just might avoid sleeping with the fishes!

Taking place in the year 1937 on the eve of World War II, the story involves a mysterious spy training organization known as the "D Agency." The organization is established by Lieutenant Colonel Yuuki from the Imperial Japanese Army. His ideals lead him to recruit people beyond military academy graduates and personnel, while training them to become skilled agents in arts of manipulation. These agents would become a specialized team to conduct operations. One such antihero agent, under the name Jirou Gamou, goes on a harrowing mission to uncover secret documents titled "Black Notes," while battling forces from within and without his own ranks.

Astro Fighter Sunred is a Japanese manga created by Makoto Kubota. It started serialization on Square Enix's seinen manga magazine Young Gangan on August 25, 2005. An anime adaptation produced by AIC A.S.T.A. aired from October 3, 2008 to March 27, 2009 in Japan. The second season of the anime started airing on October 3, 2009. Each manga chapter and anime episode is referred to as a FIGHT.

January 1999: Apprentice mage Azaka Kokutou, Mikiya's younger sister, has been ordered by her mentor, Touko Aozaki, to investigate a certain incident in which fairies steal the memories of students at Azaka's school, Reien Academy. Azaka launches an investigation with the help of Shiki.