Artist’s names: Sadamasu (貞 升 ) (occasionally (貞 益 ) and, from 5/1848, Kunimasu (國 升 ) (occasionally 國 益 ).
Active 3/1830-11/1854.
Recorded on a scroll painting dated mid 1830 (?) as a pupil of Tōto Gototei (i.e. Kunisada). Recorded on prints dated early 1834 and 3/1834 as a pupil of Tōto Kunisada, and on prints dated c. 1845, 12/1852, 8/1853 and 9/1853 as a pupil of Toyokuni (Utagawa Toyokuni III, i.e. Kunisada). He commenced his study with Kunisada between 8/1828 and 3/1830 (see below).
Recorded name change from Sadamasu to Kunimasu on prints dated 5/1848, c. 6/1848, 8/1848, and on a print dated 8/1852 published in Edo.
Surname: Utagawa (歌 川 ).
Gō (pseudonyms): Gochōsai (?) (五 蝶 斎 ), Gochōtei (五 蝶 亭 ), Gofukutei (五 蝠 亭 ), Gokatei (五 哥亭 ) (五 歌 亭 ), Ichiensai (一 園 斎 ) (一 圓斎 ), Ichijuen (一 樹 園 ), Ichijusai (?) (一 樹 斎 ), Ichijutei (一 樹 亭 ) and, in a shunga book, Yukimasu (行升 ).   
Seals: A bat-shaped seal, Ju (壽)(longevity) (placed within the shape of a bat), Sada (貞 ), Sadamasu (貞 升 ), Toshidama (年玉), Tōsui (東水), Utagawa (歌 川 ), Utagawa Kunimasu (歌 川  國 升 ), Wasa (和 三 ), and two unidentified seals.
Personal name: Kaneya (Kanaya) Wasaburō (金 屋  和 三 郎 ).
Address: Nōninbashi Matsuyamachi, Senba, Osaka (農人橋 松 屋 町 船 場 大 阪 ).

The gō Gochōsai and Ichijusai in this list, are mentioned in some sources but without any reference to specific prints.
Some impressions of Sadamasu's prints bear the hand-stamped seal Hatakumi (爪工). The seal also appears on prints designed by other artists and might not be a personal seal of Sadamasu but the seal of for instance a publisher or collector.    

Pupils of Sadamasu  

Hirosada (廣貞 ) (active 1847-1850s)
Early name: Hirokuni (廣 國 ) (early1847-5/1847)
Recorded as a pupil of Kunimasu on prints published 6/1852, 8/1852, and 8/1853 in Edo. Hirosada may be identical with Sadahiro (貞 廣 ) (as independent artist active under that name 1830-early 1847; Sadahiro is listed as a pupil of Kunisada on the memorial stone for Toyokuni I, 1828).

Kiyosada (清貞 ) (see Masunobu)

Masuharu (升 春 ) (active 1849-1850)
Recorded on a print published 1849 as a pupil of Kunimasu.

Masunobu (升 信 ) (active 1847-1851)
Early name: Kiyosada (清貞 ) (11/1847-5/1848)
Recorded on a print published 1849 as a pupil of Kunimasu.

Masusada (升 貞 ) (active 1848-1849)
Recorded on a print dated 8/1849 as a pupil of Kunimasu.

Nobukatsu (信 勝 ) (active late 1820s-late 1830s)
Early name: Shigenao (重 直 ) (until 9/1829)
Recorded on two prints dated 1/1832 as a pupil of Sadamasu.

Sadakiyo (貞 清 ) (active c. 1841)
Recorded on a painting as a pupil of Sadamasu.

Sadamasu II (貞 升 ) (active 1849)
Recorded on a print published in 1849 as a pupil of Kunimasu.  

Sadanobu (Hasegawa Sadanobu) (長 谷 川 貞 信 ) (1809-1879, active 1834-1879)
The artist is listed as a pupil of Kunisada on the Toyokuni I memorial stone, 1828. According to Onishi Komamura (in Ukiyo-e-shi, 1931, vol. 28.) and Sadanobu III (in Kamigata, 1942, vol. 138.) Hasegawa Sadanobu has been a pupil of Sadamasu for some time. In Keyes, R.S., Hirosada Ōsaka Printmaker, p. 23, note 32, a print is mentioned on which Sadanobu acknowledges Utagawa Sadamasu as his teacher. Additional details are not given.

Sadayuki (貞 雪 ) (active 1839-1841)
Recorded on two prints, dated 1/1839 and 7/1840, as a pupil of Sadamasu. 

The following artists may have been pupils of Sadamasu:
Masukuni (升 國 ) (active 1852), Masunao (升 直 ) (active 1847), Masutsuru (Shokaku) (升 鶴 ) (active 1852), and Shusho (集升 ) (active 1847).