Finding this masked, cloaked man will be rather difficult. Katanashi spends lots of time observing people from shadows. Only on rare occasions does he dawn a disguise and leave the shadows. A charm he often uses lets him sense sentience, so ambushing him is difficult. However if Jenya or Laughing Surf has conviction or compassion at 4 or greater, they will stand out to Katanashi and he will observe them.
Katanashi would likely spend a lot of time observing the market place. If an individual stands out while using Hearing the Unspoken Word, he will follow them for a while. If he suspects someone is watching/following him, he will try to lose them and observe them.