The legendary divine instrument sealed within the Ryuuteiken. The soul of the Ryuutei dwells in it, its power is above that of the Tengyokugai.
It can combine with Shouretsutei Ryuubi and can also can be equipped as separated parts by five of Ryuubi's generals. In both the manga and the Comic World version, they received this power up from the heavens during dire battles. In the manga version, Sousou remarked that the Ryuukihou appearing to aid the generals as the prove that Ryuubi is still alive.
It has the same name as the differently shaped divine instrument of Gundam Hakuryuu Taitei which was also equipped as parts by his comrades. The Ryuukihou that Ryuubi spoke to at first in his consciousness has a similar silhouette that of Hakuryuu Taitei's.