Learn Hardcore Japanese: zangyou no ato, douryou to warikan de raamen wo tabemasita. - After overtime, I ate ramen with coworkers and split the bill.

The particle の here acts as a genitive/linking particle that turns 残業 (overtime work) into a modifier for あと (after). Without の, you can’t directly connect those two nouns—残業あと would be ungrammatical.

Could you add に as in 残業のあとに? What’s the difference?

Yes, you can say 残業のあとに、同僚と… to explicitly mark the time with に. In spoken and written Japanese, however, time phrases placed at the beginning of a sentence often drop に for brevity. Both versions are correct; using に just feels a bit more formal or explicit about the timing.

Why is the subject omitted in this sentence?

Japanese frequently omits the subject when it’s clear from context. Here the speaker is describing their own actions, so 私 (I) isn’t necessary. Adding 私は would be redundant unless you want to emphasize the subject.

What does the particle と do in 同僚と?

The particle と indicates accompaniment—“with.” So 同僚と means “with a coworker.”

What does 割り勘 mean?

割り勘 (わりかん) is a noun meaning “splitting the bill” or “going Dutch.” It refers to dividing the total cost equally among the participants.

Why is there a で after 割り勘?

The particle で marks the means or method. Here 割り勘で literally means “by splitting the bill,” indicating how the payment was arranged.

Why is ラーメン marked with を?

The particle を marks the direct object of the action. Since 食べました (ate) is the verb, ラーメンを食べました means “ate ramen.”

The sentence doesn’t mention where you ate. Is that okay?

Yes. Japanese often omits details like location when they’re not crucial or already understood. If you did want to specify a place, you could add something like ラーメン屋で before ラーメンを食べました to mean “ate ramen at a ramen shop.”