Funny how the author's characters are talking about there possibly not being a volume 4. This manga apparently went on from 2003 to 2024, although I don't know if that was continuously. Author did go on a break from all her manga when she got pregnant, apparently.
I will say this: as someone who's read most of Munko's manga, Raika days is probably her best and most consistently good. 35 volumes apparently, and I'm not surprised. All of her other works have more flaws and less good characters and plotlines. Not saying they're bad by any means, I read most of them to the end... I just think Raika days is her personal best.