You should get his naturally by either going for 100% or even by just walking around town and randomly bumping into them. This can be gotten starting in chapter 4 since the city opens up for the first time here following your exit from Bacchus' bar.
http://www.gamersheroes.com/game-guides/yakuza-kiwami-substo...Linked is a completion and location guide for all sub-stories. This guide will also help you get the 30 sub-story and all sub-story related achievements.