Lagoon Engine is a manga by Yukiru Sugisaki. It was followed by Lagoon Engine Einsatz.
The main protagonists are Yen and Jin Ragun. The name "Lagoon Engine" is derived from the phonetic pronunciation of the main characters' names (Ragun Yen Jin).
Volume 6 was released on December 1, 2009. Volume 7 was released in September 2010 in the US.