For what purpose is the construction of protective walls and other artificial matter being undertaken along our coastlines? The sight of our coastlines brings this question out of many people. Answering this question immediately will probably won't lead to much and probably won't solve the problem. First lets look deeper into the roots of the problem and think about what has actually been constructed. As an example, we'll take a look at the construction on the Setohama beach in Chiba Prefecture.