Onegai Teacher is a romantic comedy and science fiction anime series that follows the story of Kei Kusanagi, a high school student who discovers that his new teacher, Mizuho Kazami, is an alien. To protect her identity, they enter a fake marriage, which gradually develops into a genuine romantic relationship. The series explores themes of love, identity, and the challenges of keeping secrets. It blends humor with heartfelt moments, appealing to fans of romance and science fiction.