Actually, Japanese pronunciation is not "furu" but "huru". The upper teeth will never touch your under lip. Remember, that we do not have "f" in Japanese. In ha-hi-hu-he-ho these is no f. Only for FEP(front end processor) to write Japanese letters on your computer, both "hu" and "fu" will be interpreted as "ふ”.

降る（ふる furu） is that one.