Giniro no Seven

A space battle romantic comedy about a high school girl, Sakuya Igarashi, and a humanoid space battleship, Seven. One day, Sakuya finds out that she's the illegitimate daughter of a star system's royal family, and she has been targeted by bandits who want to use her for political purposes. In order to protect Sakuya, Seven is sent to her high school as an undercover bodyguard.

(Source: Natalie, translated)