The elite Cosmo Academy attracts applicants from every stellar nation in the galaxy. One young hopeful is Tadatos Lane, an orphan esper from Terra. The final stage of the academy's entrance exam is a perilous mission simulation aboard an actual derelict starship. The applicants depart for the ships in groups of ten, but when Tada's crew arrives on the Esperanza, they are horrified to discover that they now number eleven. As the test progresses, things go awry and the atmosphere grows increasingly tense. The crew members begin to suspect sabotage, and Tada appears to be the likely culprit. (Source: MU)

11-nin Iru! won the 21st Shogakukan Manga Award in the Shoujo category in 1976. The series was published in English as part of VIZ Media's manga anthology Four Shoujo Stories released in March 1996, and was rereleased by Denpa on April 22, 2025. It was also released in Polish by Japonica Polonica Fantastica on January 10, 2014; and in Spanish by Tomodomo Ediciones on October 31, 2016.