OVA bundled with a special edition of the manga's 3rd volume.
The story of Onna no Sono Hoshi follows Hoshi-sensei as he experiences everyday adventures such as getting picked on by the girls in the daily classroom journal, getting saddled with looking after the class's pet dog, giving art advice to aspiring manga authors, and sometimes going out to drink with his coworkers.
(Source: Crunchyroll)