四霊のひとつ「霊亀」を討伐した盾の勇者・岩谷尚文は、別の異世界で霊亀復活の元凶であるキョウを打ち倒し、メルロマルクへ帰還する。復活間近の新たな四霊「鳳凰」との戦いに備えようとするが、霊亀騒動で失態を演じた三勇者は行方不明、尚文の持つ領地も戦力に不安が残る状況だった。今後の戦いに備えて、散り散りになった旧ルロロナ村の住民を取り戻そうと考えた尚文は、住民が奴隷として売られたというゼルトブルを訪れ、救出の足がかりとして、ラフタリア、フィーロと共に地下賭博闘技場に参加する。救いを求める亜人たち、心砕けた三勇者、そして暗躍するヴィッチことマイン。それぞれの思惑が交錯する中、尚文は自らの信じる道を突き進めるのか――
Naofumi Iwatani, the Shield Hero, who defeated one of the four spirits, the Spirit Turtle, defeats Kyo, the culprit behind the Spirit Turtle's resurrection, in another parallel world, and returns to Melromarc. He prepares for the battle against the new Four Spirits, the Phoenix, who is about to be resurrected, but the three heroes who made a blunder in the Spirit Turtle incident are missing, and the strength of Naofumi's territory is also in doubt. In preparation for the upcoming battle, Naofumi decides to bring back the scattered residents of the old Lulorona village, and visits Zeltoble, where the residents were sold as slaves. As a foothold for their rescue, he participates in an underground gambling arena with Raphtalia and Filo. Demi-humans seeking salvation, the three broken-hearted heroes, and Myne, also known as Witch, who is operating in the shadows. With their respective intentions intersecting, will Naofumi be able to forge ahead on the path he believes in?
