I think that Mishima constructs the "honor/ shame" dynamic in a manner to ensure that suicide is seen as the only possible way to salvage honor in a world where so many are either willing to live with or succumb to shame. Takeyama's situation is constructed in such a manner that he is incapable of finding any honor in a scenario with such absolutes as polarities. His own reasoning of this situation reveals this:
I shall be in command of a unit with orders to attack them. . . . I can’t do it. It's impossible to do a thing like that.
Mishima constructs this situation for his protagonist. Living within this is shame, in its own right. Takeyama is "shameful" if he betrays his fellow soldiers, and if he does not, he becomes "shameful" for betraying his Imperial Highness. It is deliberate that Mishima has constructed "shame" and "honor" in such strict polarities, without any real room for negotiation. In this dynamic, suicide is "honorable." It represents honor because it is transcendent of all other forms of consciousness where negotiation of one's ideals is part of existence. Mishima constructs the dynamic of "honor/ shame" in a way through which they are singular notions of the good. There is little manipulation in such constructs. The painstaking manner of the suicide, the glorification of it, and the almost nostalgic view through which the actual act itself is carried out are all examples of how honor is evident in suicide. For honor to be lived, Mishima suggests that suicide is transcendent, apart from a world that causes agony in individuals who wish to live the life of honor in strict and uncompromising terms.