Obito is Kakashi's friend in the Kakashi Chronicles (Naruto Anime). Kakashi was a kind of ninja who believed that rules are made to be followed, no matter what the situation is. Then in one of their mission, one of their friend was taken prisoner. Kakashi didn't want to rescue her because it is not in the rules, Obito isn't as strong as Kakashi, but he will never give up on their friend. He died trying to save her, the day of his death is the day of Kakashi's birthday, before he passed away, he gave Kakashi a gift. The gift was his left eye, the "Sharinggan". It is the perfect gift that made Kakashi what he is today, "Copy Ninja" Kakashi and the creator of Chidori. But more importantly, Kakashi learned the greatest rule of all, friendship is above any rules.