Otokichi , also known as Yamamoto Otokichi and later known as John Matthew Ottoson, was a Japanese castaway originally from the area of Onoura near modern-day Mihama, on the west coast of the Chita Peninsula in Aichi Prefecture.

A castaway is a person who is cast adrift or ashore. While the situation usually happens after a shipwreck, some people voluntarily stay behind on a desert island, either to evade captors or the world in general. A person may also be left ashore as punishment (marooned).