Hime kurabe futaba ezôshi (Picture-book comparison of twin blades and the princess: 姫競双葉絵草紙) was one of the Oguri Hangan mono or Oguri mono ("Oguri Hangan plays"). The plots were based on various legends about Oguri as well as Chikamatsu Monzaemon's (近松門左衛門) 1698 puppet play Tôryû Oguri Hangan (當世流小栗判官). Another source of inspiration was the military chronicle Kamakura daizôshi ("Great copybook of Kamakura": 鎌倉大絵双紙) concerning the master of the Hitachi Castle, Oguri Hangan no Sukeshige (小栗判官助重), and princess Terute (depending on the adaptation, Terute no Mae 照手ノまへ or Terute-hime 照天姫). Oguri's father Oguri Mitsushige, a provincial daimyô (feudal lord: 大名), failed in his revolt against the ruling Ashikaga clan, whereupon father and son were forced into hiding. Oguri's adventures follow many complicated paths, including political and military intrigues and episodes with supernatural phenomena. At one point, he is murdered with a poison administered by Terute's father and brother, but is then resurrected and takes his revenge against his wife's family.
This is one of Hirosada's relatively rare and more dynamic triptychs. Oguri on his great steed holds firm in the cresting waves while being flanked by two protagonists. Often, with such stylized waves, we are tempted to cite Hokusai as an influence, and that might very well be the case here. Even so, Hokusai was not the "inventor" of such imagery (see John Fiorillo's Hokusai page) and ukiyo-e artists in Osaka and Edo would have known other examples in prints and illustrated books going back decades.
For more about this artist, see Hirosada Biography.
References: WAS-6, p. 51, no. 226; Museum of Fine Arts, Boston (acc #11.35588a-c)