Bitter Virgin

If you still haven't read this manga after it being out and paused for a while at Volume 3, then you're either not a manga reader, or not a manga reader (meaning you DON'T read manga). So go read it now because it is one of the best mangas out there imo. If, however, you're one of those types who claim "It's not a good manga if it doesn't have swords, people, and "ki" flying around," you obviously have yet to explore the world of manga and how great it is far beyond the scope of action. Even males should read "Shoujo" manga instead of just "Shounen" manga. If you don't know what they mean, nothing's stopping you, and even if you know what they mean, put yourself up to the task of uncovering the greatness of manga.

So go read it now if you haven't done so.

Other great series:
Spiral: Bonds of Reasoning
Ichigo 100% (Strawberry 100%)
Black Cat
Gintama
Fullmetal Alchemist
Pretty Face
A Record of Fallen Vampire (haven't found an English tl of this yet, so unfortunate for non-Japanese readers)