The set of the MIDDOGARUTSU side A and Side B. There was a separate MSX2 and MSX2+ edition. The MSX2+ edition has smooth scroll and a different intro. There are also differences in boss battles and it uses the Kanji ROM for some texts (eg, the disk change text)
Note: for extra confusion, the MSX2 edition actually says "MSX2/MSX2+" on the box, this only means it is compatible, not that it has the smooth scroll.