SHIGEKO'S DOSSIER: Yellow - or "Captain Yellow" as she prefers to be called - is the captain of a riverboat that plies the waters between The City of the Rich Frog and the Scorpion Clan Palace. Her vessel is called the Bullfrog, and she makes Ryoko Owari her port of call because her sponsor is Shosuro Gobei (P4). Gobei seems more concerned with ensuring a steady supply of his wares both up and down the river than he is with strictly enforcing his right of taxation upon her.
I strongly suspect that she has a secondary business - smuggling. It may be a coincidence that she often schedules a voyage when there is an intense criminal manhunt in the city. I have never found fugitives or passengers without papers hiding on her ship - but when she takes one of her conveniently timed voyages, the criminal sought has a way of never turning up at all.