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I was told if the lead singer is english/japanese their music is going to english.

like Ellegarden or Oceanlane

This true?

Well maybe? I think Hikaru Utada has lived in America almost her whole life and she does a mix of English and Japanese so I don't know.

Utada Hikaru spent her whole life moving back and forth between Japan and New York. Just to let you know. Also she didn't know how to write (music) in Japanese before her first CD. She also wants to be famous in Japan and America.
It's like Melody. She was born and bred in Hawaii came to Japan and now she's becoming famous. On her new CD she remade an english song (in english) and also has a few other songs in english. It's good for everyone really. English is the main stream so it's amazing that more artist don't sing in both languages.

Also, It depends. Not all mixes speak english. Like Eiji Wentz of WAT. His father is a german american yet he can't speak english at all, haha. sweatdrop

So some of them will put out some english songs. Some of them will and some won't it depends on the band type and their comfort level.

English sales though. Japan is pretty hot for it. haha.