Gintsui no Alexandra (Volume)

is the first volume of the Gintsui no Alexandra light novel series, written by Yu Ueno and Illustrated by Iseno Yajin. It was released under the Dengeki Bunko Imprint in November 2007.

Synopsis
One night, it was Xandra, a girl with a huge hammer, who saved Kosuke, who was seriously injured by a mysterious creature. In order to save her Kosuke, she embeds "Magic Stone", which is the source of her own magical power, in Kosuke's body. Xandra, who calls herself a wizard who has chased a "demon beast" who breaks through the "boundary of dimensions" from another "world", settles in Kosuke's room with the shield of being her lifesaver. Kosuke is being swayed by Xandra, who has a big attitude and a strong appetite. Eventually, a demon beast appears in the city again, but Xandra's magic stone is still inside Kosuke's body, and she can't use magic! Kosuke challenges the demon beast to save Xandra.

(source: Bookwalker JP - Translated)