[@KoL] In terms of special areas/districts, Hikaru is in Adachi and Shiori is in Shinagawa.

Also yeah, feel free to challenge either one.

EDIT: If it's convenient for you, I can have either take a train to your character's location.

EDIT 2: Also, if you're looking to challenge the Yellow King, just try to find him in the Network. Jon Warbles is a fairly large fellow, and if you ask, he'll tell you whether or not he has the game, what his standing is, etc.