Drawn on cardboard. Found in box of Mazda replacement parts. Circa 1976
While working at Mazda Motors I found this enclosed with auto parts.
Thank you for submitting your item for appraisal. This appears to be a feltpen drawing by an unknown amateur artist who worked at a spare parts / tool port 工具遣場 in Japan. The drawing is congruent with the provenance you described. It is impossible to decipher the internal joke which is depicted here.
I assume the sentimental value will be much higher than any potential monetary value.