The World's Strongest Rearguard: Labyrinth Country's Novice Seeker, Vol. 4 (Manga), Paperback

Down in the uncharted depths of the Field of Dawn, the gang faces off against the "Eagle-Headed Warrior" Named Monster protecting his domain. Arihito manages to save his friends from the monster's crushing power, but takes a fatal blow since his defensive barrier doesn't work on himself...