Chrome Shelled Regios Wiki
Titles & Brief Synopsis
Regios Crusade Vol
Dixerio Maskane is the protagonist for this spin-off series.

A three-volume, science-fiction light-novel series that is set in the world of the Chrome Shelled Regios series. Dixerio is featured in the cover of the first volume.

This series covers the background of Dixerio, beyond time and space where he fought with the Wolf Brigade. A story that fits between the events of Legend of Regios and Chrome Shelled Regios.

Regios Crusade vol.1 - Sleepless Tombs
In the future of Layfon and friends, comes a connection of a new regios world!
Dick, a resident of avarice city Velzenheim, meets a girl named Janice while travelling on a roaming bus. Janice has a man to kill so she says, which happens to be -- Lintence!
Regios Crusade vol.2 - Endless Phantoms
Staged in Zuellni, a regios side-story.
Dick's fight against the Wolf-Mask group continues. Dick goes to Academic City Zuellni and experiences student life. There, he meets two girls, Shiari and Reian.
Regios Crusade vol.3 - Neverending Luminance
Therefore, the end result is Chrome Shelled Regios!

After the meeting and parting at Zuellni, Dick still dedicates himself to fighting the Wolf-Mask group. Dick reunites with Reian, who has travelled back and forth in time and space, once more in Zuellni. Soon, what lies ahead for Dick is revenge while he found the meaning of his existence.

Source :Wikipedia JP + Japanese site