The term 'Promo' can have been applied to a wide range of sample materials circulated at the time of release. We won't be able to answer questions regarding specs, and we do not accept returns on promo items so please buy at your own risk.
The fourth album, released in 1980, was a 10-inch mini album that included "TIGHTEN UP," which was later re-cut as a single. It was a groundbreaking work at the time, with comedy skits by the Snakeman Show inserted between songs. It felt more like a "planned" album than an original album.
At the time of release, he was so busy that he didn't have time to create many songs, so he released it as a 10-inch mini album. After Yukihiro Takahashi played his favorite radio program, "Snakeman Show" for Haruomi Hosono, it became a comedy album with comedy skits between songs.