Literally, 黒歴史 (kurorekishi) means “black history”, and this is something that you are desperate to eliminate from your mind.
黒歴史 (kurorekishi) indicates humiliating and excruciating behaviour that one conducted in the past. Everyone is desperate to forget such painful memories, but unfortunately there are always a certain number of jerks who persistently make fun of your 黒歴史 and assist them to remain vividly in your heart for good.
Typically, people end up making 黒歴史 when they are teenagers, and regret the ignorant behaviour for the rest of their lives. To make matters worse, a myriad of people publish their 黒歴史 on the Internet and share the wonderful memories with people all over the world.
The term 黒歴史 (Kuro Rekishi) is said to originate from the Japanese popular anime ‘Turn A Gundam’. In the Anime, the era of the ‘Universal Century’ was named ‘黒歴史’, namely ‘black history’ or ‘dark history’, to emphasise the dark side of the period that saw a great number of space wars. The Universal Century is the timeline when the series prior to ‘Turn A Gundam’ are set in. In contrast to the Universal Century, the timeline of ‘Turn A Gundam’ is called the ‘Correct Century’ a.k.a ‘Seireki (正暦)’.
Note that the pronunciation of 正暦 (Seireki) is the same as ‘西暦’, meaning ‘western calendar (A.D.)’ and it is somewhat confusing. For instance, A.D. 2018 is called ‘西暦 2018’. The difference of these words is that ‘正’ in 正暦 means ‘correct’ while ‘西’ in ‘西暦’ means ‘west’ or ‘western’. The common character ‘暦’ means ‘calendar’ or ‘almanac’, and ‘和暦’ means ‘Japanese calendar ‘ with 和 meaning ‘Japanese’.
黒歴史 consists of the two words: 黒 means “black” and 歴史 means “history”. Therefore, its literal meaning is “black history” and indicates the dark side of your history you want to forget. This word is mainly used on the internet, but some young people also use it in real life.
It is a complete 黒歴史 that I uploaded my sh*tty rap music videos on YouTube when I was in junior high school.
Jerk: Hey dude, I’ve heard that, back in high school, you asked out ten girls in the same class in one day and got rejected by all of them. lol
You: Oh stop it, don’t remind me of my f*cking 黒歴史
It is my 黒歴史 that back in high school I wrote on my blog about how crazy I was about this girl.
(* Most of the people who make a ‘Koukou Debut’ end up generating a number of 黒歴史.)
Synonyms and Related Expressions
Synonyms: トラウマ (trauma), 過去の汚点 (past faults)
Synonyms in English: dark history, trauma, mental scars
Related words and phrases: 黒 (black), 歴史 (history)