SERENTIA is a country that is the last resort for human beings after WWIII. After the war, the survivors all suffer an incurable mental trauma, similar to PTSD. In SERENTIA, they can forget their trauma within a certain time limit and move on to live a normal life again. In SERENTIA, time is the currency. People need to work to get more time because the more time they have, the longer they can forget about the trauma. If their currency runs low, they start to suffer flashbacks.