I had this as a part of the Mega Games 2 cartridge for my Mega Drive as a kid. Mobygames says that it was only available as a pack in with the Mega Drive 2, and never for sale separately. I must have bought it second hand as I had the original model with the headphone socket on the front.
I didn’t get very far as a child, definitely not past round 2 but I think I beat the first boss. It’s a very hard game, but one that actually becomes reasonably easy once you’ve learnt all of the enemy locations and behaviours.
This time I played it with RetroArch and managed to collect all of the retro achievements in hardcode mode. This means that you have to play it as it would be on an original machine, i.e. no save states, rewind, fast forward. The one where you beat the final boss on the hard skill level without using your magic is by far the hardest I think.
It has an excellent soundtrack, particularly the song for round 1, it’s written by Yuzo Koshiro who also did Streets of Rage 2 and ActRaiser which are also fantastic.