I Got Caught Up In a Hero Summons, but the Other World was at Peace! (Manga) Vol. 4

Looking forward to a change of scenery and short vacation, Kaito and his friends head to the elven city of Rigfaurecia for their Treasure Tree Festival. The event is in full swing and everyone is enjoying themselves, but none know that danger lurks just beyond the city walls. When monsters descend upon the city and wreak havoc on the festivities and participants, old traumas are triggered. Though he rushes in to help, Kaito is soon the one needing assistance! Will his friends be able to rekindle their slumbering skills to save him?