I was about to say that for 黒歴史 to have no negative connotation is really odd since I've always heard it being talked about in reference to one's past works (videos, writings, drawings, etc.) that one regards as "not so great" due to one's natural improvement over time, but now that I've read the Wikipedia page, it turns out that I was probably simply misunderstanding things.
Okay, the Wikipedia page does say that in internet slang, 黒歴史 could possibly mean "things that I wish are gone" (note the present tense), but it could also possibly mean "things that are now gone" (this would refer to the past), and that nowadays, the meaning has broadened to include the idea of "things that, not due to anyone's intentions but 'just somehow,' have ended up being forgotten or weathered away."
So perhaps it meant something more like "though it's now part of a long-gone past" rather than "dark/regretful past."
last edited at Dec 26, 2016 10:38AM