Among it many other luminaries were the great landscape artist Hiroshige, Kunisada, Kuniyoshi and Yoshitoshi (the last great master of woodblock prints).
In the main Utagawa school of woodblock artists, there was eventually a whole series of go (art-names), from most senior to junior. As each senior person died, the rest would all move up a step!
The head of the school generally used the go (and signed his prints) as "Toyokuni"; after Kunisada I took over as head of the school (in 1842 or so), he started signing as "Toyokuni", and the next most senior member, Kochoro, started signing as "Kunisada" (Kunisada II, in this case).
The next most senior member after him, in turn, began signing as "Kunimasa" (Kunimasa IV, in this case), which had been Kochoro's go before he became Kunisada II. (The original Kunimasa I had been a student of Toyokuni I.)
Here is a list of some members of the main Utagawa school, giving the succession of names used by some of them, along with the modern numbering of each:
One final additional complexity is caused by the fact that there are two different artists who are sometimes referred to as "Toyokuni II".
The first Toyokuni II was Toyoshige, a mediocre pupil and son-in-law of Toyokuni I who had taken over as head of the Utagawa school after Toyokuni I died.
Kunisada I (Toyokuni III) despised Toyoshige, and refused to acknowledge him as head of the Utagawa school. Apparently, this was because he felt that as the best pupil, he should have been named head after the old master died, and was upset with Toyoshige, who apparently got the position because of his family connection.
When Kunisada I took over the art-name Toyokuni (in about 1842), he "removed" Toyokuni II from house history and for a period actually signed as "Toyokuni II". Everyone now numbers him Toyokuni III, though. So one needs to be careful, as there are prints which are signed "Toyokuni II" but which are actually by the artist we now call Toyokuni III.
This numbering persisted, so when Kochoro became head of the Utagawa school, he signed as "Toyokuni III", although by our counting he's Toyokuni IV; and likewise Kochoro II eventually signed as "Toyokuni IV", when we number him as Toyokuni V.The Utagawa School and Inherited Art-Names
The Two Different Toyokuni "II"s