Lillia to Treize: Soshite Futari wa Ryoko ni Itta  

Lillia & Treize, リリアとトレイズ -そして二人は旅行に行った-

Lillia to Treize: Soshite Futari wa Ryoko ni Itta is based on Keiichi Sigsawa's light novel series Lillia to Treize.