It came to me a few weeks ago, when I found myself in grave danger. I wasn't taught how to do it, but I believe I have an idea on how I turned able to use it, if what I heard is any indication.

[High school occultism, is the likely answer. The first Persona games had the characters get their Personas because they played the Persona ritual, and somehow, this is one of the few cases in fiction where kids doing a strange ritual ended positively]