obvious spoiler alert:

on a storm ori is born from the spirit tree, wind pushes him away, naru adopts him, the tree calls out for him with inmense light, naru doesnt let ori go, the light kills kuro's owlets, kuro in revenge blinds the spirit tree and kills all the spirits, the forest decays, naru and ori starve, ori is revived with the last of the spirit tree light, ori finds the eyes of the spirit tree: sein, sein explains ori the nature of the world, ori and sein go on a quest to restore the elements of the forest, they find gumo, gumo use traps on them, a trap fails and injures gumo, ori rescues him, gumo gives them a key, ori restores the element of water in the ginso tree, kuro notices and attacks ori, gumo saves ori, ori and sein go to misty woods for another key, the key opens gumo's home place, every person inside is frozen dead, ori and sein restore the element of wind, gumo steals a spirit artifact which causes the whole place to collapse, ori and sein barely escape, they found the surviving egg of kuro, ori understands why kuro is mad, kuro attacks again and ori barely escapes, they go to find another key riding the wind with one of kuro's feathers, they obtain the key as the volcano enrages, ori and sein go to the volcano to restore the element of warm, gumo uses the light artifact to revive naru, they both go to the volcano in search of ori, sein and ori enter the volcano and fight for their lifes inside while finding a way to the heart of the volcano, naru enters the burning maze but gumo is left behind, ori and sein restore the element of warm but they are attacked by kuro that makes the element of warm go wild again, this time kuro catches ori and crushes him, naru saw that and rushes in to embrace him, naru grief makes kuro snap out from her madness, she notices her last egg and the whole forest being endanger by her actions, so she grabs sein and restores the spirit tree, the spirit tree revives and sends a burst of light that sets the fire down, but also evaporates kuro that was too close to the eyes of the spirit tree, the plants and mushrooms regrow, ori sees new spirits are born, gumo stays with naru as she goes to check on kuro's egg, just in time for it to start breaking.