User blog comment:B214/Question and Answers 6/@comment-185.112.105.215-20160622160723/@comment-94.5.128.78-20160623001054

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Yes Sirzechs has Bahamut as a servant, he's a Rook. The difference is between this Bahamut and the one from Bahamut the anime is the one from DxD is the actual mythological Bahamut and the other one is just a dragon with the name.