Board Thread:Questions and Answers/@comment-27885184-20130728211558/@comment-917693-20130728214132

As Reol said, you can use google translate. I think it has a romanizing option. (Just make sure to change macrons to their "normal letters" counterpart and change words that are used to describe english words to their english counterparts. e.g. gaaru → girl)

And additionally you can look at the external links (most likely twitter name) they are in romaji and the official thing. (e.g. Cocolu would "with normal standard romanization" be kokoru, but looking at her twitter, she'd like it to be cocolu instead.)

And if the name is in kanji but you know some kana (or have a list of katakanas as reference), you can go to the respective utaite's nico nico pedia page (usually there's a link of them in the tags) and on the tabs, you can see the name in katakana in brackets.