Yen works as a sort of currency for the site. You earn more for each day you are part of the site and for posting in certain areas, I may award people with more Yen if they do certain things (Such as bring us another member or win a fight in the RP) but I may also take Yen away for breaking the rules.
What you can use it for: Yen can be used for a number of different things, such as
*100 Yen= A minor change to your accepted profile (Such as another ability)
*200 Yen= A free pass for breaking ONE rule, ONE time
*300 Yen= A major change to your accepted profile
*500 Yen= The changing of your character to another race
*800 Yen= The creation (addition) of a race of your choosing
*1000 Yen= A special place on the forum just for you, such as a mansion or house (the only ones permitted to post in this place will be you and a few others of your choice)
Other prizes may be added at a later date