Oh, this will be huge soon. I don't know how soon, but it will be. It has the neverending plot like Naruto and One Piece. For Naruto, it's 'I will become Hokage!' which takes very very long. For One Piece, it's 'I will become the King of Pirates!' which also is not easy. And for 666 Satan, it's 'I will take over the world!' which is the most arduous of all
This of course is not a bad thing whatsoever, I'm just pointing out the similarity.
I was actually surprised how light-hearted this manga is, considering the title. I've been following it since Toriyama World only started. It's great!