木村：S君にも困ったものだね。陰で僕の悪口を言いふらすんだ。
田中：気をつけた方がいいよ。あいつは執念深いっていう噂だから。
Shuunen bukai
Kimura: S-kun ni mo komatta mono da ne. Kage de boku no warukuchi wo ii-furasun da.
Tanaka: Ki wo tsuketa hoo go ii yo. Aitsu wa shuunen-bukai tte iu uwasa dakara.
Kimura: That Mr. S is a real problem. He's saying all sorts of things about me behind my back.
Tanaka: You should be careful of him. He has a reputation for being rather vindictive.
The expression shuunen bukai
refers to someone who is unforgiving, who always bears a grudge, who is spiteful, vindictive or tenacious in their pursuit of revenge.
In Japanese, take wo watta yoo na seikaku (clean-cut personality) is often used in commending a man's character. The expression derives its meaning from the fact that when you split (waru) a piece of bamboo (take), it splits clearly right down to the base.
Then in contrast, there is the rather derogatory expression, onna mitai ni nechi-nechi shita seikaku (a clinging, tenacious character like a woman). Although I, as a woman myself, find the expression discriminatory, it might have some truth in it as it survived in the language for so long.
Ano hito wa ne ni motsu taibu de shuunen bukai. (He/she is a kind of person who clings onto little things, and will never Let you forget.) The expression can be referred to either men or women, but in Japanese literature, it is al- most invariably used to describe women.
In the Tale of Genji, there is a female character who kills the woman Genii loves bv outtine a curse on her - this is an exampfe of shuunen bukai josei ga sum koto (the kind of thing a spiteful woman would do).
Also most Japanese ghosts tend to be women. Since it wasn't easy for women to express their thoughts openly and behave as they wished in society, they came back as ghosts to speak their minds - Shuunen bukaku narazaru wo enai. (They had no choice but to save up their grievances in the hope of getting revenge later.) This is something of the background to the current use of the expression.