Children's meijin tournament?

[tuulentupa]

In one of those side stories of vol 18 we meet the bratty child meijin. Can anyone tell me if there really is this kind of children's meijin tournament, and what it's like? I'm mainly wondering what the age limits are. For fic writing purposes, naturally. :) I've tried to google but all I can find (in English) are Hikago links...

...I know I've had other things in my mind I was thinking I could ask here, but do I remember them now? Of course not.