Ishirou has always collected maps as a hobby. When Borben befriended the cantankerous Tian man, he shared this hobby with the halfling monk and shared a secret.
He compared one of his maps to the map salvaged from the Jenivere of Smuggler’s Shiv. It appears that the islands line up and the island may be home to a buried treasure. He would love to help find it and is willing to share the treasure with all that help. Sharing treasure with him in this way will instantly change his attitude to Helpful.
Once Ishirou is made Helpful, he can teach a PC his swordsmanship techniques, granting anyone that practices with him for a full day a permanent +1 bonus to CMB and CMD while weidling a sword.