Kanzo Hattori aka Hattori-kun, is the protagonist of the series, a little ninja.
He is 11 years old and 40 kg and is 140 cm tall. He is the boy who usually contests Kemumaki when he performs pranks.

Hattori's main weakness is that he is afraid of frogs; this often leads him into trouble. He wears blue coloured ninja robes. He always explains what a good ninja does and likes meddling in his friends' business. His powers can be compared to a master ninja.

He also has a strange habit of saying ~degozaru or nin nin after almost every sentence. His girlfriend seems to be Tsubame.

(Source: Wikipedia)