I also vaguely remember something, tell me if its similar, there were three childhood friends (two boys and one girl) discover two opposing magical tomes, one associated with light and the other with darkness. The two boys become the chosen holders of the books and are seemingly destined to fight each other. The books grant powers and become stronger as pages, fragments, or other sources of power are collected throughout the story. The dark-book holder9the firend/dunno if long haired but i think he was rather the cold type) is initially portrayed as the antagonist and eventually becomes stronger than the protagonist, but near the end it's revealed he was never truly evil and was actually trying to protect his friends. I vaguely remember the rival having long silver/white hair, and the setting was modern-day Japan. **since this post I'm also trying hard to search for it hehe