Of course the name is normally written in kanji, but the way it is pronounced can be expressed with hiragana, and that's how it would be done. Like it or not, there is a u.
I?
Edit: When special letters are unavailable (me, for example, I don't know how to make the macron, I have to copy it from somewhere), it's more correct to use ou than just o. And even if I had the macron, I'd probably still use this way. I prefer the traditional Hepburn romanization system to the modified one.