I've only ever met 2 Japanese people (aside from stuff like teachers and whatnot) and got close with neither, but one of them was very willing to discuss more negative aspects of her life =/. Nothing too personal, since we'd only met the day before, but stuff like how her job had been wearing her out and what not. She'd spent the past 1-2 years abroad though, so that might have affected things.
The other one, on the other hand, was very willing to completely avoid any negativity. He'd casually mention him being robbed or (we only assume this) having a horrible heart condition and maybe dying soon. It was weird.
(actually, make that 3 people. But one was a Penticostal that ended his negative story with a song about Jesus, so I got mixed feelings about it...)