ongoing legal dispute between TMS and the estate of  Maurice LeBlanc (who had authored the original "Arsene Lupin"  stories that the Lupin III character was based upon), TMS had  stipulated in licensing contracts with American companies that the  name "Lupin" could not be used in marketing or translations.  AnimEigo (distributor of this OAV in the US) complied with the  contract and instead chose a literal romanization of the Katakana in  Lupins Japanese name: "Rupan." Although the legal dispute has been  settled (partly because all but the last of the Lupin stories have  fallen into public domain), Animeigo still honors the terms of their  license with TMS 