Disaster planning challenges our morality. Everyday rules of action may need to be suspended during large-scale disasters in favour of maxims that that may make prudential or practical sense and may even be morally preferable but emotionally hard to accept, such as tsunami-tendenko. This maxim dictates that the individual not stay and help others but run and preserve his or her life instead. Tsunami-tendenko became well known after the great East Japan earthquake on 11 March 2011, when almost all the (...) elementary and junior high school students in one city survived the tsunami because they acted on this maxim that had been taught for several years. While tsunami-tendenko has been praised, two criticisms of it merit careful consideration: one, that the maxim is selfish and immoral; and two, that it goes against the natural tendency to try to save others in dire need. In this paper, I will explain the concept of tsunami-tendenko and then respond to these criticisms. Such ethical analysis is essential for dispelling confusion and doubts about evacuation policies in a disaster. (shrink)