After his cooking battle escalated to open warfare, the Shield Hero Naofumi has finally obtained the truth about the Vanguards of the Waves. After the Demon Dragon takes a liking to Naofumi, she proposes heading to a castle located on the continent that she once ruled. Once there Naofumi and his party are attacked by thugs pretending to be treasure hunters, but they swiftly deal with this threat, leading to Naofumi squaring off with S'yne's sister and Witch herself. Faced with foes wielding both holy and vassal weapons obtained by illicit means, the Demon Dragon makes an alarming suggestion - for Naofumi to unleash the power of his rage!