The equivalent to Korean ~버렸어 in Japanese seems to be ~ちゃった.
Examples:
食べちゃった＝먹어버렸어
死んじゃった＝죽어버렸어
忘れちゃった＝잊어버렸어
However, this seems to only work in the past tense and as an informal/oral expression.
The Chinese equivalent, by the way: ~掉了 as in 吃掉了.
Formal expression: ~します
食べてしましました (...maybe?)
