がしんしょうたん
going through thick and thin to attain one's objective; enduring unspeakable hardships for the sake of vengeance
Noun, Suru verb, Intransitive
私わたしは長ながい間あいだ臥薪嘗胆がしんしょうたんの苦くるしみをなめた。
I have struggled under extreme difficulties for a long time.