The general consensus is that Shiki is very young (due to how often she's portrayed as a loli), but in my head, I can see her being a petite 20- or 25-year-old. There's nothing saying the judges of heaven are immortal, or that one doesn't replace another when one dies.
...I will love you for all my life.It's Love! Love!And yet...I wonder...will we get along well?Do you still want me even so?Blussssh...You realize I'm going to cry, right?But, I mean, when you consider my true age, I'm an old lady, aren't I?Never fear. Even if everyone tries to make you out as an old lady or a fool...