Himawari!(2006)

Himawari! is an anime series following a spirited girl determined to become a ninja after being rescued by one in childhood. On her first day at ninja school, she meets Hayato, an unlikely instructor working off a debt who isn't actually a ninja himself. The discovery that Hayato bears an identical mark on his neck to her mysterious savior sets the stage for an unexpected connection between them. As Himawari trains alongside her classmates, the mystery of Hayato's past and his link to her childhood rescue gradually unfolds, blending action, comedy, and coming-of-age themes with hints of romance.