Yoshimitsu's first appearance was in 1994's original Tekken. Kunimitsu's story in Tekken 2 reveals that Yoshimitsu's blade is passed down through the Manji Clan's leaders. The clan is dedicated to a mission to help the weak and fight the oppression.
About one hour after cooking. After that, any food can become tainted and needs to be refrigerated to keep the bacteria in control. If it is uncooked, it needs to remain refrigerated-but will only remain fresh in this state for about 2 or 3 days at most.
As to the absolute time cooked meat will keep, it depends on the storage temperature and the amount of water left in the meat. I think most people just feel after four or five days that something about it just puts them off. So, except for mistakes, few people ever keep it around until it actually spoils.