These "specials" should instead be referred to as three animated trailers for the manga Zekkyou Gakkyuu. Or even advertisements, since the source material is not new.
Each trailer showcases what appears to be an arc or maybe even a chapter of the manga, and ends on a cliffhanger. Although this is an obvious form of advertisement, it does do its job effectively. These trailers made me interested in the source material, and now I plan to read it.
Since these trailers did their job rather well, I recommend that you watch them (at least trailers 2 and 3) and see for yourself if you are interested in reading the source material.
