Which camera lens should i bring for travelling?

Take the wide angle lens. You can always crop the shots if you want to emphasize detail. Wide angle lenses are easier to focus and if you know how to use depth of field, you can do away with focusing by just leaving the focus to manual with a certain aperture. You can make up zoom by walking nearer to your subject but it is harder to go wide specially in cramp spaces like in Japan. You'll love the wide angle. It'll give you more elements in your shots.