Is this from a doujin? Anyone know the source?

Er, it should be Akane-SAN not -tan.

Its writen Tan here. Itrs a cute/childish way of saying chan

What's the deal with that circle in the bottom left text bubble, third character from the bottom in the right column. Is that kanji for pussy or is it some kind of censorship character?

Vasuki said:
Is that kanji for pussy or is it some kind of censorship character?

The latter.

Ranranrun said:
The latter.

That's what I figured, thanks for the confirmation. :D