Skeleton Knight in Another World (Manga) Vol. 2

Arc resolved to live his new life as a skeleton as inconspicuously as possible, but after a chance encounter with the elf warrior Ariane, he chucked his hesitation right out the window. Elves are being treated like slaves, and Arc will have none of it. The Skeleton Knight takes up their righteous cause...and prepares to assault their human overlord's castle!