Some sources say this artist was active 1832-1852.
Sadamasu (1834-1848); Kunimasu, a name change as early as 1/1848. [This information comes directly from Osakaprints.com. However, there appears to be a glaring mistake in this information, because although they give Sadamasu's dates of 1834-48 they must have meant that this was his signature during those years only.]
Utagawa Kunimasu (formerly Sadamasu; active late 1820s-early 1850s) was said to be a wealthy real estate owner in the Semba district of Osaka who developed his own school of printmaking. He was a fine artist who has been credited with developing the fully mature Osaka style of chūban format actor bust portraits (ōkubi-e, or "large head prints"), designing his first example around 1837. (The earliest known single-sheet chūban in a well-developed Osaka style were designed by Shōkōsai Hanbei (active c. 1795-1809), two full-length designs published in 9/1799.) Prints by Kunimasu are encountered less often than those by many other Osaka artists, although they are not rare. He was a friend and patron of Hirosada and various other artists. Hirosada seems to have considered Kunimasu his teacher, or at least a significant collaborator, although the Edo master Kunisada (1786-1865) played a more important role as a teacher to both these artists. Hirosada traveled to Edo around 1826-27 to study with Kunisada, and Kunimasu followed around 1830; they returned together to Osaka in 1834. In 1852 both Kunimasu and Hirosada revisited Edo and collaborated on a series of half-length actor portraits by Kunisada titled Edo murasaki gojūyonchō ("Fifty-four Chapters of Edo Purple"). After this trip Kunimasu apparently gave up print design for painting.
Along with Hirosada, who was the most important and prolific mid-nineteenth century printmaker in Osaka, Kunimasu explored the psychology and emotions portrayed by actors on the kabuki stage. Hirosada took this approach to its greatest extent in mid-nineteenth century Osaka printmaking, expressing the psychology of stage performance through powerful and varied physiognomies and vivid or unusual placements of the figures in his compositions. It was one of Hirosada's important contributions to ukiyo-e, and Kunimasu played a role in developing this approach toward actor portraiture.
This information is taken directly from OsakaPrints.com
Personal name Kanaya Wasaburô; Osaka address Nôninbashi Matsuyamachi, Senba cited in a directory of Osaka called Osaka shôkô meika shû; pupil of Utagawa Kunisada I (recorded on a print dated 3/1834).
Said to have been a wealthy artist/teacher who supported the work of artists in his studio; skilled Osaka print designer in his own right; after 1852 apparently turned to painting in the Shijō style.
Pupils included Nobukatsu; Masunobu; Masuharu; Sadanobu; Sadamasu II; Hirosada; Masusada(?); Masutsuru(?); Sadayoshi(?); Masunao(?); Sadayuki