This pen is a bit of an enigma to me, as my resources for older Japanese pens are scanty. The model number I assume from the only marking on the body of the pen apart from the maker’s name. I have access to a Sailor catalogue of unclear date (“the Seventies” is not something you’d want to plug in as a target for your time machine), which shows things of much the same shape and properties, but with different model numbers.
Concerning shape and properties, this is one of the “pocket” style pens that came into fashion in Japan in the early 1960s and remained in some maker’s line-ups as late as the 1980s. The point is somewhat unusual, with a gold content of 21K. I say somewhat, because while the industry standard for gold content in points is generally 14K or 18K, Sailor habitually uses 21K in their production. This started in 1969 or 1970, as part of a contest between Japanese pen-makers over who could have the highest gold content in their points, running right up to a slightly ludicrous 23.99K in one example, which ran through much of the 1970s. There is no functional advantage to high gold content in the points, apart from a reduced likelihood of discoloration (one occasionally sees a ruddy tarnish appear on older 14K points), but there is a slightly enhanced risk of damage when the softer metal gets into a heavy set of hands.
My example of this model has a fairly firm point, which is probably wise; a “soft” point might entice a writer into over-stressing the tines. Balancing the possible frailty of the point, the cap is a very sturdy item, similar in feel and likely in material to that of the standard Parker “51”. Sailor is another company which has resisted the urge to make old pens unusable by changing their cartridges, so current refills will work in this pen.
Production Run: c.1969 to c. 1975. Apart from knowing when the gold content of the point started to appear and a vague sense of when “long/short” pens were being made, this is a pure guess, and anyone with firmer data will be embraced warmly should they let me know.
Cost When New: ¥2000, based on three very similar pens of the same price in that catalogue I mention. In 1970, that would be the equivalent of of about $5.50 (for modern value, try this calculator). If it were available for export, the price would likely be higher outside Japan.
Size: 11.8 cm long capped, 14.6 cm posted, 9.9 cm uncapped.
Point: 21K gold.
Filler: Cartridge, capacity approx. 1.2 ml
If you are relying on the preceding information to win a bet or impress a teacher, you should read the site’s scholarly caveat. Remember, this is the internet, and it’s full of bad information.