A collection of Dragon Kishidan oneshots and side stories:

One Day, Another Day
Set before the end of the series, it's basically a side story of a day in the Dragon Castle, kind of in Zoma's perspective.

Juuji ni Hikaru Hoshi
Takes place before the events of the actual series. This is a back story that shows how Lykouleon and Raselane met, introducing Lykouleon's uncle, Fieruto.

Mamono no Mori no Kioku
Another backstory that delves a little bit more into the relationship between Bierrez and Cesia before the series started. It also shows how Nadil became the demon lord.

Happiest Children
This actually has three little side stories in it. The first one is about Rune's dream about everyone dressed in drag, the second is about a little adventure that the three dragons go on, and then the third is like a day in the life of Alfeegi, Ri-ma, and Duma.

Crescendo
Backstory about how Lykouleon and Kaistern met and how Kaistern then became the Blue Dragon Officer.

CONFESSION - Thats
This is basically the backstory of Thatz and how he knew about Rath's little secret.

CONFESSION - Rath
Basically telling a lot about Rath, particularly his relationship with Kaister. + More