The World of the Emperor's Key

"The World of the Emperor's Key" (『皇の鍵』の世界) is an instrumental musical composition from the Japanese version of Yu-Gi-Oh! ZEXAL.

It has been released on Yu-Gi-Oh! ZEXAL Sound Duel 1.

Appearances
"Harto Tenjo's Theme" was played in following episodes:
 * Yu-Gi-Oh! ZEXAL - Episode 003
 * Yu-Gi-Oh! ZEXAL - Episode 010