The Final Decisive X'mas Battle!!

is volume 21 of the Beelzebub manga.

Contents

 * 180. The Tournament Starts!!
 * 181. Showdown! The Strongest Couple!!
 * 182. Fierce Battle!! Best 8
 * 183. Ishiyama Showdown!!
 * 184. Semifinals! VS Tōjō!
 * 185. The Final Decisive X'mas Battle!! 1
 * 186. The Final Decisive X'mas Battle!! 2
 * 187. Trial!
 * 188. Restored Den of Delinquents