In Japan "Lord of the Rings" is just as popular as in other countries. The title is a phonetic transcription of the English title. Now, as many of you may know, the Japanese have a sound that falls directly between English "L" and "R", and makes it simultaneously impossible for most Japanese to say either, and equally impossible for them to tell the difference between them in phonetic transcriptions. Thus:

"Lord of the Rings" becomes "Lodo obu za Lingu"

The problem lies with Lodo and the L<->R confusion. Lodo can also mean "road", or "street", both of which are arguably more common words than lord. Throw in the small fact that Japanese doesn't have a plural form for words, and the translation naturally becomes "Road of the Ring". As this fits quite nicely with the story, the mistaken translation goes completely unquestioned.