Kyouko is 14 (in Youkai terms), Mamizou is probably about 43 (again, in Youkai terms), and I'm not too sure of Nazrin or Ichirin, but Ichirin looks about 32 physically. Nue is (about) 11 (in Youkai terms, about 1143 in Human terms), Minamitsu is 1569 (but physically 20-something). In all seriousness, though, they both predate the Heian Period and Hiragana, and possibly Þ. Murasa's probably as old as Nero...