From MAL:

During the Edo period, not all samurai were considered wealthy, high class war heroes who answered directly to the shogun. In fact, many of them were of low rank and remained nameless throughout their careers while living economically with their small families just to make ends meet. Nakamura Hanshirou and Yukie with their baby son Tarou is one such family, and through their lives, Yamato Waki offers eye-opening glimpses of the less talked about aspects of living in Japan's capital during this famous era.

Note: Vol. 2 contains a 3-chapter long side story titled "Aoba Shigereru" that involve the same set of main characters.