User blog comment:B214/Volume 23 discussion blog/@comment-24502975-20170203153821/@comment-9595671-20170208034619

We kinda have to have a villain since at most we'll be having another 8 volumes, so a lack of a villain would make things pretty stale and dull when the series hasn't reached it's end just yet.

Plus Indra wants to have his war with Shiva and he's the only one of the three gods (Hades and Loki being the others) who's caused problems for many that hasn't faced any consequences. He's been a villain since Volume 11-12, he just hasn't really acted yet, and this tournament is where he's likely thinking to start his act.