When I think "mainstream" I usually think names that even people who haven't seen it would still recognize through their popularity one way or another. Something that escapes purely weeb boards and has name recognition even among the casuals.

NHK was big at the time the anime was happening, but its otherwise not seen much talk outside the weeb places. And even then only the anime, trying to talk about the manga or the novel (and how hugely different both are) will get a lot of confusion.

Which sucks, because the novel is the best form of the story and some of the changes are massively for the worst, like making Satou a virgin (taking away a huge cause of his stunted development caused by the one time with his senpai) or removing his constant apathy and complete disconnect from things happening around him most of the time (while his overreactions are funny, him being a barely eating, drug abusing shell of a hermit would not leave him with the constant energy he shows in other versions).

I really think the anime only got as big as it did because it turned Misaki into a pure waifu for lonely weebs and added an amount of romantic comedy angles, instead of her being an insane, controlling BPD (literally confirmed) nutcase in the manga and the barely described wistful thing she was in the novel.

Though manga NHK is incredibly deranged once it stops being an adaptation and creates an entirely new final third of the story. The "Hyper Self Pleasure" scene alone is pure insanity.