Its been a while since I read James Clavell's original novel. But I do remember the 1980 TV version with Richard Chamberlain and Toshiro Mifune was classic. If anyone can remotely compare to Mifune, it would be Hiroyuki Sanada, so at least they seem to cast the part of Toranaga Yoshii right with Sanada.
Clavell's novel was remarkable for its time in how it accurately nailed down that particular history of Japan, the Sengoku period, when the country was torn by warring daimyos (warlords), each commanding their own army of samurai clan, vying to gain supeme power and re-unite the country.