Sulu isn't a Japanese name, for the record. There is no "l" in Japanese (many Japanese can't even pronounce it), but "Hikaru" is (it means "light").
Actually, there is no "r" either. Itīs actually a sound that could be described as "between l and r" (if you look at the tounge position), when beeing transcribed into our writing system it can be written as "l" OR "r". To our western ears it sounds like "l" or "r" or it can even seem to alternate between both.