The plot is enigmatic - the main character has made a vow, but we never find out what the vow is, or whether it explains his odd behaviour. It seems to have something to do with his haircut. Someone is murdered, but we never find out by whom or why. Although reference is made to evidence of guilt, this is never revealed. The emotional engagement is very cold.
The milieu is strange. It is set in 19th century Japan, but because of the isolationist embargo there is no modern technology. There is an armed rebellion going on, but nobody has smuggled in Western firearms. The buildings and art work are ravishing, even in an army barracks. The sexual morality is somewhat like Ancient Greece. I don't know how accurate any of this is: other stories I have seen set in this historical period seem quite different, with Japan in more of a transitional and unsettled state.
The way the story is told is hard for me to understand. Voice-over and screens of text are used to deliver inconsequential information, while vital facts are not explained. For example a screen card appears with the words 'The captain of the guard also desired Kano' and then we see the Captain of the guard - plug ugly and massive - marching past with his guards. Then the character never appears again or is referenced in any way.
A final point is that the beautiful boy who tears the regiment apart with jealousy (erm, I think) looks more like a girl than he would in any western film on the same subject. His face is so very soft and pretty ('bishounen') that it is slightly disconcerting. Perhaps this is the intention.
Perhaps if I watched it again I would understand it better.