While preventing suicides is a universally difficult task, it is particularly challenging in Japan. Depression remains a taboo topic here, making it hard for those most at risk to seek the help of family and friends. Many Japanese view suicide as an issue of private choice rather than public health, and there are few efforts to highlight the problem.
There are a cornucopia of arguments for why we might want to discourage suicide. Cases in which we might are in a dynamic world with shifting preferences, and in which a private means of "tying Odysseus to the mast" is absent. Or where individuals have incomplete knowledge about the present and future. These are conditions under which potential suicides would be better off with prevention.
But suicide can represent an advantageous lower bound on utility. With that in mind, we may not want to prevent all suicides. This situation is graphically depicted below (click to enlarge).
(click to enlarge).