Boris’s behavior suggests he is not afraid of Mamiya or death. Mamiya’s failure to kill Boris results in a feeling of shame that he is never able to shake. It is a large reason why Toru finds Mamiya in such a broken state. It is one final indignity that Mamiya suffered as the war ended. To make matters worse, Mamiya returns home to find his family dead, so he truly has nothing and no one else to care about. From this moment on, his existence turns into suffering.