Believers

On a small island somewhere near Japan, three cult members have devoted themselves to the "Deserted Island Program". Calling each other by rank, these people-two men and one women-have been chosen by their superiors to throw off the corrupt influence of modern society and "purify" themselves. But as time passes two of the members begin to give into human desire.
(Source: MDL)
~~ Adapted from the manga series "Believers" (ビリーバーズ) by Yamamoto Naoki (山本直樹).