Did this on hard first try on lvl 58. Was much easier than dragons. Opponent not using dekaja nor dekunda was his demise. My team was protagonist elementalist. Junah persona master. Heismay ninja and Hulkenberg trickster. I used Junah to inflict thunder weakness (and sometimes use inherited dekaja to clean opponent buffs) and attacked with protagonist synthesis Skyfall Bolt. Heismay whole role was using inherited knight proclamation and quick-change arts on extra turns. With dodger ring equiped he depleted all turns icons for enemy with each dodge (which happened often). Hulkenberg was only casting debilitate to decrease enemy stats and sometimes dekaja for cleansing buffs. I used items for healing and one cooked item which gave concentrate to protagonist for extra dmg (which due to maxed inteligence and lowered defence dealt about 8.5k dmg).