The spelling has changed a couple of times with translators but it's always been some variation of Johan (pronounced yo-hon). I think he's half german or something.
Thanks for telling me
I know another character with the name Yohan. Isn't that just a normal korean name?
Yes and no. I believe that name came from germanic influences so just like Peter exists in english, Pierre is it's french counterpart meaning that a name can originate from a different region. East Asian languages tend to be more pictographic and have symbolized characters rather than letters so translation is a bit different when it comes to that. That's why the name Johan, Yohan, etc can all have the same spelling in korean because their characters are more sound based than letter based.
Anyways, due to this, it's possible that Yohan has become a normal korean name but it's also possible that it's actually the Korean version of Johan as they would both be spelled the same way in korean. But funnily enough, Johan is just the German version of the English name John so I find it odd that Korean society would not put their own cultural spin on the name.
Okay so I did some more researching and Yo-han is the Korean version of the name John, Johan, etc. The difference here is that to specify it as the Korean version, there's a hyphen as it's spelled with a character for each syllable, making it literally Yo and han instead of Yohan. So that's where the translation here with all the different name spellings in english gets a little wonky and is why I said yes and no for my explanation above. It essentially relies on the translator's knowledge of different languages and the difference between writing Johan, Yohan, and Yo-han. Since we don't know much about the main character's life, i would think that the last one is supposed to be his name but it doesn't really matter because, again, they are all pronounced the same way and should, to my knowledge, be spelt the same way in Korean even if they aren't in english.
Hm ... interesting!
Was his name always yohan? or was I just not paying attention