I think that's only if you're in Tokyo. It's often said [0] that people living in Kanto/Tokyo are cold. I've been here a decade now, mostly out in halfway rural/urban areas and it's not uncommon to randomly strike up a conversion with a stranger. Probably not as common as in the US/Aus, but definitely not a rare event.

[0] https://www.google.co.jp/search?q=関東人が冷たい&aqs=chrome..69i57....