I think it's chapter 7. It's the Beagle one directly after the Tosa one. You have to mark 3 locations in Shibuya suburbs, then return to the Boss Beagle. But I'm completely stuck because I can't find a way back to the Boss Beagle. Every path is blocked off. I'm near the bottom left corner of the map. I can't go back the way I came because there was a bit where there's a ramp one side, but no way to jump back up the other way.