He's become so soft that he has no sense of adventure now at all. But if a man lives in the forest, there are things he has to do! That's why I'm determined to get him to build a new bridge. I'm sure he can do it.Karude
Amaterasu and Issun first meet Kokari in Agata Forest, where Kokari worries about his lost dog, Ume, in the Tsuta Ruins. After rescuing Ume, Amaterasu helps Kokari with a variety of tasks, including helping him catch fish, most notably the Giant Salmon. Later in the story, Amaterasu must help him catch Whopper, the legendary fish, to save Ume (again), and recover the Crescent Celestial Brush Technique. After Amaterasu slays Orochi, he takes part in the Kamiki Festival and tells her that he won't be in the forest anymore and, instead, will be traveling across the land. Kokari travels across Nippon afterwards, ultimately ending up in Kamui.
Upon first meeting him, Kokari comes off as a crybaby, unconfident, and a bit of a coward. However, after Amaterasu saves his dog Ume from Tsuta Ruins, he becomes more sure of himself and sets out to fix the bridge that connects Agata Forest with Taka Pass. He also learns, from Ume, to be more adventurous since he was too timid to do anything that may put his and/or Ume's safety at risk.
Later on, after the defeat of Orochi, he realizes that his life was rather insignificant and wanted to do more, and become "a real man like Susano." He really grows from a crybaby to a more mature person. This is evident when Amaterasu meets him again in Kamui. He tells her that the forest was good but that it was nothing compared to the harsh nature of Kamui. This could also mean that he's become more connected with nature.
Kokari is a very small, short boy with short, black hair and a curved unibrow. He is recognizable by his rabbit skin coat that is very similar to his father's. The rabbit skin coat Kokari wears is orange, with a backpack strap running through the middle to help support his backpack. He also is always found with the fishing pole he carries to fish with; Kokari is almost always seen next to a river or a large body of water. Lastly, he has a small rabbit hat on his head.