Difficult one. I remember being told about hentai by everyone who saw me drawing manga on my notebooks before I knew what it was and seeing some DBZ porn someone brought to school from their home printer. I know that at some point I bit the bullet and checked it out, and that it was a long string of google searches but i don't recall the first one. I know it was naruto characters names followed by the word hentai and hentay since I didn't knew the correct spelling. I know the first Doujjin i read was an Eyeshield 21 one about Mamimi teaching the main character how to have sex and I genuinely am glad it was that because I carried the knowledge of what a clitoris is with me from the very beginning.