The Book of Gelel (ゲレルの書, Gereru no Sho) is a tome passed down from the royal family of a distant continent.
The book contains all secrets of the Stone of Gelel, including:
- how to control its power.
- the history of Temujin's people and the developments they attained with the aid of the Stone's power.
- the story of how the power of Gelel came to be discovered and used by Temujin's ancestors.
It does not, however, contain information on how to destroy the stone.
The book followed Temujin's ancestors over the sea and later came into the possession of Haido (claiming he bought it from a travelling merchant, to which Kahiko doubted it was so simple) who started to use its secrets for evil purposes. The book is lost when it was left aboard Haido's airship, which was sucked into the Space–Time Hole.