[Seele]

Japanese names are a big mystery for me. May be it's a little offtop, but since you're discussing names as a whole, I have a question that disturbes me a lot.))
There's a singer 田中聖 and last kanji reads like Koki, but in the dictionary there's no such reading for it, only せい & ひじり. And even when you write it on computer Koki doesn't become this kanji. So I have to write Tanaka Sei 0_0

Question: why is it read like Koki? I'm going crazy from it. x)

Well, so as not to be totally offtop, for my name Olga is オリガ or　オルガ better? Or no difference?