Kohaku is the daughter of the Ninja Leader in her village. She has eight brothers and sisters, but they all died during missions from wounds and illnesses. She is also the childhood friend of Aoba, Hayate and Shuri. In the final volume, she was chosen to become the next Ninja Leader and Aoba congratulated her.
Kohaku (琥珀) means "Amber" in Japanese.
Kohaku has emerald eyes and medium blonde hair that is usually tied into two pigtails on each side of her head with two blue ribbons.
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 received from Prince Oura (Aoba). Kohaku is also quite clumsy and is described by Hayate that she is a big lummox.
Kohaku is a incredible Ninja that showed great strength when she fought with Shuri. Hayate is very pleased and proud of Kohaku because rumours has it that she better than the current leader of the ninja Village. Kohaku excels in fire, water and flying techniques. Also, she was able to master the transformation technique when she was 10 years old. This technique is difficult for even a adult Ninja could master! When Kohaku was only five years old, she was a huge crybaby and she unconfident because she showed fear in front of her father and that she thought she didn't have the strength of becoming a true ninja. She also trained with Aoba, Hayate and Shuri when they were childhood friends. When Aoba came by, she was very happy and she trained with the others. However, her father wouldn't allow her to call Oura's name by his childhood name because he is the Prince and he was needed to stay in the village for his health. Kohaku cries and tells the story to Hayate and Shuri. Shuri cheers her up by saying, "Just keep smiling Kohaku. Use that as a camouflage and just keep smiling". Hayate gets frustrated because Shuri is an awfully shy person who would say these things. This is when Kohaku vowed to never cry. When Aoba departs, Kohaku called him Aoba. Aoba gets angry because she thought Kohaku and the others were different but in fact, they weren't. Kohaku cries and smiles in front of him by saying "Goodbye, Prince Oura."
When Kohaku reached to 10 years old, she becomes more mature and dependant. However, she is extremely angry of Hayate because whenever Aoba showed up, he would call him by his Prince name in front of everyone. But whenever they're alone, he would call him his real name, which leads to Kohaku's frustration. However, Kohaku knows that Hayate is a kind boy at heart.
Kohaku and Hayate met out together because Kohaku wanted to confess her feelings to him. But, she was awfully shy and her face turned red. Hayate wonders what's with her and ask her if she was hungry. Kohaku reply and says no and she tries to spit out her words in front of him to confess to him but was too nervous and so, she stuttered. Funnily, her stomach made a noise and she felt embarrassed so she said never mind to Hayate and walks off looking displeased. Hayate tries to stops her and says to her."Wait, it's something important isn't it?" Since we're alone. we might as well kiss". Kohaku's face went furious and she calls Hayate an idiot and she used the jutsu on him and suddenly he transformed into a frog. Kohaku and Hayate faces were shocked. The Leader, who was furious, called out to Kohaku and asked her to break the jutsu. Hayate explains and says "It's okay, boss, she tried nearly 30 times before she ran away" while Hayate looking depressed.