there's one sound in Japanese which is somewhere between L and R, though probably closer to R.
- Luffy/Ruffy (One Piece)
- Lio/Rio (Kara no Kyoukai)
2 of the Vocaloids are the twins Rin and Len, but given the above, their names could be Rin and Ren, Lin and Len, or even Lin and Ren.
So where did it become known that Rin's and Len's names have different first letters, as opposed to the alternatives that I mentioned?