What is Lupin III's nationality?
Most of the sources stated that Lupin III is half-French, half-Japanese - sources: 1, 2, 3, 4. There are also sources that state that his nationality is unknown - sources: 1, 2. But according to this:


  Lupin is half-French, half-Japanese, though Monkey Punch, Lupin's creator himself said (in materials to promote the first Lupin movie) that he considered Lupin to be of no nationality – a citizen of the world.