Many lighters were made in and marked Occupied Japan subsequent to World War 2 while the U.S. occupied the country. The ones in this category were made during that time period and not otherwise identified by a company name. Japan was considered 'occupied' from their surrender August 14, 1945 through the official end of occupation on April 28, 1952.
Bullet Keychain Lighter
Occupied Japan c. 1949 Weston made an identical lighter in New York, possibly before shifting production to post-war Japan for this one, which is unidentified as to manufacturer. KIK-0AC
Federal (as in US Armed Forces, not a brand name) Belt Buckle Lighter
c. late 1940s - mid 1950s. Often the lighter portion (picture to right) of this belt buckle set is sold on eBay as just an "interesting" or unbranded lighter. The buckle / lighter is for a narrow belt (1"). The same buckle lighters were produced during the period of occupation and subsequent to that. The later buckle lighters just say 'Japan' as opposed to 'Occupied Japan' on the earlier models. This lighter may be slipped over a belt and may be positioned anywhere on the belt with a narrow 1" belt - though that wasn't what it was designed for. It is designed for use as a buckle when used with a belt having a snap loop at the end to hold the buckle.
The HUGE Lift Arm table lighter pictured below is virtually identical to the Grant lift arm lighter (See: Grant). This is also identical to a lighter marked with the manufacturer name Reliance - but this one has no identifying name.