As the looming threat of another Wave approaches rapidly, Naofumi Iwatani and his comrades find themselves pressed for time. Unexpected disruptions in Lurolona Village and the mysterious halt in the countdown to the impending Wave prompt the Four Cardinal Heroes to regroup urgently with Queen Mirelia Q Melromarc. The queen suspects a connection between these disturbances and the reawakening of the dreaded Spirit Tortoise, a malevolent entity bent on wreaking havoc once more. A daring strategy to subdue the Spirit Tortoise is proposed, but to the dismay of all, only the burdened Shield Hero is willing to lend his aid among the quartet of chosen defenders.