People on the One Manga discussion board were really surprised that Bitter Virgin was able to not only take #4 on the Top Viewed Manga list, but keep it's spot for a long time. Even though it's dropped in popularity recently, it's still on the list at #19.
I think the reason that it's so popular is that the first chapter just sucks you right in. Sure, it starts off like any other romantic seinen manga, but then they drop this huge bomb on you! The general theme is one that's fairly common in manga in general, (Leading male meets leading girl, isn't really interested, then finds out something about her that makes him eventually fall for her.) but Aikawa's something is just intense that it almost shatters the mold completely. I had to re-read page 26 several times just to get over the shock.
My one grief with the series is how it ended. Without spoiling it for anyone, the general attitude that all of the characters have when everything is said and done really just pissed me off.
only mods get to use color, ya dirty weeaboo