Kekkaishi Vol. 8 (manga)

With the help of their new kekkaishi-in-arms Gen, Yoshimori and Tokine battle the Dark Watchtower, a mysterious cabal of hideous ayakashi demons, to defend Yoshimori's ancestral lands! But the three friends are badly outnumbered, and when Gen's fury causes him to go too far, they may lose him forever--in more ways than one...