"Hikaru to Hikaru" is a comedy about Hikaru Katsuragi, a boy who is a descendant of the Iga ninja, sneaking into a girls' school.
In the Katsuragi family, if you don't master the secret "Kunoichi no Jutsu," which turns your body into a female body, by the age of 18, you won't be recognized as an adult, and his mother was worried about Hikaru's immature technique.
In order for such a Hikaru to become a full-fledged woman, he is ordered to attend a prestigious school for young ladies, Kazami Girls' School, in the form of a woman.