The female lead of the story. After she was rescued by a ninja with an odd mark on his neck, she swore to become a ninja; her dream is to become a great "Kunoichi" (female ninja) despite her classmates doubting her abilities.

Himawari Hinata recently transfered to Shinobi Gakuen to train to become the best kunoichi she can be. She wanted to be a ninja ever since she was saved by one when she was little. On her first day, she meets Hayato Madenokoji (a new transfer teacher) who saves her life. Hayato does not possess any ninja skills or traits, he is teaching the ninjas about normal society to pay off his debt. However, Himawari notices that Hayato bares the same mark on his neck as the ninja who saved her when she was young.
 
(Source: Anime News Network)

Himawari is back in all her comical ninja mischief. The sequel to Himiwari continues with the many odd and hilarious adventures of Himawari, Hayate and her Ninja classmates. Season two delves into Himawari and Hayate's Past. Will new secrets be revealed? Will Himawari finally find out about her past and the mysterious ninja that saved her when she was little?
 
(Source: Anime News Network)

Himawari! is the story of Himawari and her journey to become a Kunoichi, and her 'vow' to protect her master. Himawari Hinata recently transferred to Shinobi Gakuen to train to become the best Kunoichi she can be. She wanted to be a ninja ever since she was saved by one when she was little. On her first day, she meets Hayato Madenokoji (a new transfer teacher) who saves her life. Hayato does not possess any ninja skills or traits, he is teaching the ninjas about normal society to pay off his debt. However, Himawari notices that Hayato bares the same mark on his neck as the ninja who saved her when she was young. 
(Source: M-U, Wikipedia)