A renewal search was done in books, periodicals and artwork for the years 1966 and 1967. There were no listings for any title with "Mikado" in it for these years and renewal categories. There's no evidence of copyright on this item.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.