Lillia and Treize

is a Japanese light novel series written by Keiichi Sigsawa, with illustrations by Kouhaku Kuroboshi. The series began publication on March 10, 2005 by ASCII Media Works under their Dengeki Bunko publishing imprint.

Synopsis
Lillia, a 15-year-old girl who lives with her military mother, Allison. There, a childhood friend, Treize, came to play during the summer vacation. Lillia casually touches Treize, but at the suggestion of her mother, Allison, who was forced to leave her house due to her sudden training, she decided to go on a trip together. However, the two will have a great experience on that trip ...

Characters

 * Lillianne Aicasia Corazón Whittington Schultz (Lillia)
 * Treize Bain
 * Allison Whittington
 * Wilhelm Schultz (Wil)
 * Carr Benedict
 * Fiona
 * Megmica Strauski (Meg)

Manga Volumes
The Manga Adaptation of the Light novel, illustrated by Hiroki Haruse was serialised in Comic Sylph and released under the Dengeki Comics Imprint beginning April, 2008.

Anime
An anime adaptation of 'Allison' and 'Lillia and Treize', produced by Studio Madhouse. It aired for 26 episodes between April 3, 2008 and October 2, 2008.
 * see: Allison and Lillia (Anime).

Related Series
Lillia and Treize is part of the Tales of a Single Continent series alongside:
 * Allison
 * Meg and Seron
 * Hitotsu no Tairiku no Monogatari