That specific niche always makes me laugh because of its inherent contradiction. The Icha Icha series is basically the 'Forbidden Scrolls' gag turned into a running joke. The best fics don't just have Kakashi reading it; they explore the why. Like, why would a man so deeply traumatized, a professional with PTSD, keep rereading what amounts to erotic pulp? Is it a weird form of dissociation, a tether to his teacher, or just his way of maintaining a 'normal' front that's as fake as the stories themselves? I've read one called 'Legacy in Orange Ink' where the Icha Icha books are coded messages from Minato, containing intel or sentimental notes in the margins, and Kakashi's reading is actually a form of grief-stricken code-breaking. It reframed the whole thing. Another good one is 'A Field Guide to Flower Arrangement,' a Kakashi/Sakura slow-burn where Sakura secretly writes a rival, botanically-accurate erotic series under a pen name, and Kakashi, being Kakashi, figures it out and starts leaving her anonymous, hilariously pedantic critiques about plant physiology. It's less about the smut and more about their weird intellectual courtship.
You have to sift through a lot of crack-fic where he's just a pervert, which feels like a shallow read of the character. The ones that dig deeper, using the books as a lens into his isolation or his connection to the past, are where the gold is. I tend to avoid the ones where he's writing it himself, unless it's a crack premise done exceptionally well—most of those just aren't my cup of tea.