Sessue Hayakawa has a challenge from his very first scene which is not to be forgotten next to Alec Guinness's formidable performance as their characters go head to head from the earliest moments of the film. Hayakawa not only manages not to be forgotten but also manages to be just as memorable as Guinness in these scenes. They go full force with their codes to one another both in a similar yet different fashion that creates a fascinating dynamic between the two performances.
Hayakawa as Saito who has all the power is far more forceful with his implementation of his code. Hayakawa is great because he shows just how ingrained the whole idea of the Bushido warrior code is in Saito. It is clearly something that has been impressed on him his entire life so much that no matter what he cannot shake the code he feels he must go by which most importantly deals with the idea of a soldier dying before even failing.
Hayakawa has a great presence and force of will that appropriately matches Guinness'. The difference though is Guinnness always stays British and proper whereas Hayakawa is far more forceful intensely repeating his demands to attempt to get his way. Although like Nicholson Saito is really insane with his devotion to his code Hayakawa is absolutely believable in this insanity that is prevails is an entirely calculated and controlled man.
Hayakawa is appropriately brutal but in an entirely military fashion. He never thinks a second thought of what he is doing, even almost having several men killed in an especially calm and simple fashion showing that Saito has gone all the way many many times before. Saito is always the soldier first and that is where his cruelty comes from, and his idea that the British for surrendering are not soldiers anymore, Hayakawa is particularly great showing an incredible pride in the escaped soldiers who were killed, because to him they were soldiers again. This sounds insane and it is, but Hayakawa shows that to Saito it is the absolute truth.
Hayakawa is interesting because like Guinness he manages to pull humor out of his character despite the fact that Saito is almost entirely no nonsense. Hayakawa though brings this humor to the part without it ever seeming out of character. He really shows this well in his scene where he tries to act nice to Guinness to get his way by attempting to pander to Nicholson by making a few concessions. Hayakawa is just great in the way the usually brutal man quietly and kindly asks Nicholson to go along with the way he runs the camp.
Hayakawa performance truly excels though because he does not make Saito a one dimensional Japanese commander devoted to Bushido. He most certainly is this but a man of his own as well. The interesting aspect of his performance is the fact that he really never wanted to be a career soldier. He was rather pushed it into by his father. Hayakawa shows Saito is still a devoted soldier, but because of his past he subtly shows that he himself is scared by his devotion to Bushido knowing that even though he really does not want to he will have to kill himself either way, this aspect of Saito is given few words but is completely realized by Hayakawa.
It is in this aspect of the performance that Hayakawa is especially brilliant because he manages to create sympathy for this cruel villain. After he loses the camp to Nicholson Hayakawa manages to make me feel sorry for him actually since he has been so ingrained in his code he can't help it. In the second half of his performance Hayakawa performance almost becomes entirely silent, but still manages to create this sympathy. He shows a depression in Saito who has left his fate to Nicholson. Hayakawa has been a sad sad man no longer able to control his environment as he had before. It would have been easy to not care about this cruel man but Hayakawa realizes Saito so well particularly his past that makes it easy to feel for a man who has lost everything at the end. Saito could have been a one note character, but Hayakawa manages to bring him completely to life in a performance that works as a perfect compliment to Guinness' s performance making a perfect supporting performance.