There are three episodes in the OVA and they mainly cover the backstories of Kija, the Hakuryuu (white dragon), and Zeno, the Ouryuu (yellow dragon).
The first episode shows the activities of the group in a hot spring in the middle of the mountains and also shows the reason behind the many scars on Kija's back. This is adapted from the 12th volume of the manga known as "Upon that back" and "Kija".
The second and third episode cover Zeno's backstory and give a glimpse of King Hiryuu and how Hiryuu castle came to be. Zeno's powers are also revealed in these episodes.They are a summary of the 21st and 22nd volumes of the manga and cover the Zeno arc. The heartwarming relationship between the first generation of dragons and king Hiryuu shines a light on why Zeno shows nostalgia when he meets the Dark Dragon and the Happy Hungry Bunch.