佐藤：私、今月いっぱいで、会社を辞めさせていただきます。
木村：今辞められると、プロジェクト計画が続きませんよ。 ちょっと無責任じやありませんか。
Mu-sekinin
Sato: Watashi, kongetsu-ippai de, kaisha wo yamesasete itadakimasu.
Kimura: Ima yamerareru to, purojekuto keikaku ga tsuzukimasen yo. Chotto mu-sekinin ja arimasen ka.
Sato: I'm going to quit this company at the end of the month.
Kimura: If you leave now, we won't be able to finish the project. Don't you think you're acting a bit irresponsibly?
Mu-sekinin means lacking a sense of responsibility. There are many words in Japanese that use the prefix mu- in this way to add the meaning of "lacking in" or "without." A few examples are mu-kankei (unrelated), mu-rikai (lack of understanding), muda (waste), and mushi (ignore).
In Japan, where the lifetime employment system is so common, it's only in usually rare cases that employees hand in their resignation. Recently though, there have been more cases of top quality employees being headhunted as they often are in the United States.
Sato-san held a leading role in the computer company he worked for. But then he was invited to work for a rival company with much better conditions of employment. Ima no shigoto wo tochuu de yameru no wa mu-sekinin daroo ka (Would it be irresponsible of me to quit my current work in the middle of everything?) he asked himself over and over again.
He also asked his wife what she thought, and she told him, "You've put in overtime every day of your life for the sake of your company. Thanks to you they've produced a successful new line of software that must have made quite a profit for them. And yet in spite of that your salary has stayed the same as everyone else's. Ima, taishoku suru koto ga, keshite mu-sekinin to wa omowanai wa (I don't think it's at all irresponsible of you to quit now.)"
That's right, he thought. You only live once. I'm going to move to a company where I'll be appreciated for what I'm worth. And so he moved to the rival company. But after hearing that the project at his previous company had broken up without him, he started to have doubts. Jibun no shita koto wa, mu-sekinin na koto datta no daroo ka (I wonder if what I did was irresponsible of me) he still asks himself.