Chapters F and L were two bonus episodes released on the DVDs. Chapter F covers Mayama's work place and, peripherally, Ayu, and Chapter L covers Lohmeyer, a fellow tenant of Mayama, Takemoto, and Morita's.
They succeed in taking the crazy-ass humor of the series to new levels, and cover some material from the manga that wasn't covered in the series.
Overall, a nice addition to the series to tide you over till the second season.