Tenku no Arcamiles IV Castra no Ryoshu

is the fourth volume of the Tenku no Arcamiles light novel series, written by En Mikami and Illustrated by Sumi Keiichi. It was released under the Dengeki Bunko Imprint in March 2007.

Synopsis
Reina, who was under the spiritual control of Grossman, is back in front of Takuya and his friends looking for clues to the Clan Terion's base, "Castle." Reina, whose memory is sealed and raging as a thug of Terion, and Miseria Fortes, a "golden warrior", are in her hands. Takuya, who cannot fight Reina, has no choice. Hinako realizes that her Reina's spear is directed only at herself, and in order to protect Takuya, she goes on a strategy to lure Reina alone. While avoiding Reina's pursuit, Hinako headed for ... Finally just before the climax !!

(source: Bookwalker JP - Translated)