Compare the Japanese with the difficulty of 'l' vs 'r'. And an obligatory Babylon 5 scene with Zathras - https://youtu.be/1j-76eLz1hc?t=1m40s
This comparison is not apt. Japanese has neither l nor r; the sound commonly transliterated as "r" is a different sound.
By way of http://ell.stackexchange.com/questions/112384/do-all-native-...
> However, even before their first birthdays, babies begin to lose the ability to hear the distinctions among phonemes in languages other than their own.
From http://www.encyclopedia.com/media/encyclopedias-almanacs-tra...
Compare the Japanese with the difficulty of 'l' vs 'r'. And an obligatory Babylon 5 scene with Zathras - https://youtu.be/1j-76eLz1hc?t=1m40s