@KING JAIMY Something like "Eyenn". It's hard to write out a pronunciation since it's one syllable. But, I guess it's kinda like saying the word "I'm" but with an "N".
@Number 13 You're not the only one. I hate when people say his name like Ian. lol It's Ein like in Einstein. No ones says E-an stein, at least as far as I know.
His name is based on the german word for 'one', which Hitomi (who is from Germany) gave him.
So just get an online dictionary that offers a service to listen on how the german word 'ein' is pronounced and you know how he's called. Hitomi is also saying his name during the story mode btw.
I pronounce it the German way too. By the way, Hitomi didn't give Ein his name. It was a codename made up by DOATEC. Ein is just short for Project Epsilon.
"As a result of the traumatic events, Hayate gained extreme amnesia and couldn't even remember his own name. While he was staying with Hitomi and her father, he was named "Ein" and worked in the family's dojo, mastering karate in a short period of time."