I came across these two sets of characters:- じ (ji) and ぢ(ji) and ず(zu) and づ(zu). As they sound very similar but with different characters, at what times would it be the right to use any of them as they have the same sounds and for which words? For example, for the word, hajimimashite はじみまして, how come じ is used instead of ぢ but have the same sound?
It only depends on the word. " づ " and " ぢ " are pretty rare, but exists and are exactly pronounced like "ず" and "じ". You don't have to be confused. It's just variations you may meet.
I was confused, too until I took a good look at English spelling. Learning how to spell Japanese is much simpler by comparison. When you become comfortable enough reading hiragana that you can stop comparing to romaji, it gets easier! Good luck with your studies. :)
ok, thanks :)