Amazon Japan has a very different image of me as a customer. While I’ve overtrained Amazon US to the point that it uses the most tenuous and obscure connections to come up with recommendations, the Japanese site has no such difficulty. I get the occasional curveball after I’ve used it as a search engine for obscure words, but for the most part, recommendations are plausibly based on things I’ve actually bought.
In this case, because I once tossed a few random light novels (mostly still-unread) into an order, including one called School Succubus Panic (in which the titular succubi are available in maid, catgirl, vampire, meganekko teacher, and other flavors; why, yes, it is porn), Amazon Japan just sent me a recommendation for Imouto no Rippubaajin wa Onii-chan no Mono. I had to click through just to see if I’d parsed it correctly…
The word is "lip virgin", making the title translate roughly as "Younger Sister's First Blowjob Goes To Her Older Brother". The description makes it clear that this is her idea, and she's training hard so she can satisfy him fully and cure his "solo" problem.
It is currently rank 1,319 in the books category, although that’s probably because it was released yesterday, not because it’s a future best-seller. I don’t think I need to own a copy…