Brand: Tombow Pencil Co.
Made in: Japan
Oooh, 05's in the house! Tombow put out quite a few variations of the mono in the 70's-80's. The design series will have an 01, 02, 03, 04 and the newly discovered 05.
This Japanese company was founded in 1913 and is still manufacturing fine writing instruments more than 100 years later.