Death March to the Parallel World Rhapsody, Vol. 9 (manga)

Looking to deliver a letter from the Witch of the Forest of Illusions, Satou and his party decide to visit the village of the forest giants. He soon finds the villagers are still recovering from hydra attacks, including three children who were poisoned by the hydra's toxic breath. As Satou gets to work on brewing an antidote, Karina ponders how she can enlist the giants' assistance in ridding her hometown of the demonic presence that plagues it...