Kohaku is a very caring, bubbly and loving person who will protect her friends when required to do so or when she wants to. Kohaku was first introduced with Hayate when helping Princess Sakura heal after the wound she recieved from Prince Oura (Aoba).
A somewhat klutzy ninja but she showed great strength in being able to fight Shuri, who used to be her friend. Kohaku has feelings for Hayate, but can't tell him because she feels guilty for using jutsu to accidentally turn him into a frog. After the jutsu broke (thanks to Rurijo) she confesses to Hayate, but is rejected since he fell in love with Rurijo.
Kohaku's name, 琥珀, means "Amber" in Japanese.