Kawanabe Ky??sai is cool. There is no doubt about it.
But probably we should start with the term of ‘Ukiyo-e’. Ukiyo-e is a genre of Japanese art mainly made 17th-19th centuries. While most European artworks around the same period were created for the rich clients, Ukiyo-e was made to please the commoners in Edo (now Tokyo). The artists produced a lot of prints to distribute at affordable cost. Some Ukiyo-e went viral, and some artists became very famous.
The most famous Ukiyo-e artist is Katsushika Hokusai. Even if you have no interest in Japanese art, probably you have seen this big wave. Yes, it is one of Ukiyo-e.