Learn Hardcore Japanese: asa ni koohii wo nomimasu.

に is the time particle that marks a specific point when something happens. Here it indicates you drink coffee in the morning. For parts of the day like 朝, adding に is grammatically correct, though you can sometimes drop it (e.g. 朝、コーヒーを飲みます) in casual speech.

Can we omit に and just say 朝コーヒーを飲みます?

Yes. In everyday conversation you often see 朝、コーヒーを飲みます with a pause (comma) instead of に. Saying 朝コーヒーを飲みます is also understandable, though using a comma or に can make the time clearer.

What’s the difference between 朝にコーヒーを飲みます and 毎朝コーヒーを飲みます?

毎朝 means every morning, so 毎朝コーヒーを飲みます explicitly states a daily habit. 朝に just tells you when you drink coffee (in the morning) but doesn’t inherently specify frequency.

Can I say コーヒーを朝に飲みます instead?

Grammatically it works, but it’s unnatural. Time expressions almost always come at the start of the sentence in Japanese. The natural order is 朝にコーヒーを飲みます (or 朝、コーヒーを飲みます).

Why is を used before 飲みます?

を marks the direct object of a transitive verb. Here コーヒー is what you are drinking, so it takes を before the verb 飲みます.

Where is the subject in 朝にコーヒーを飲みます? Why isn’t 私 included?

Japanese often omits the subject when it’s clear from context. Here it’s understood as I. You can add 私は for emphasis or clarity (私は朝にコーヒーを飲みます), but it’s not required.

Why is 飲みます at the end of the sentence?

Japanese follows a Subject–Object–Verb (SOV) order. Verbs come last, so you list the time (朝に), then the object (コーヒーを), and finish with the action (飲みます).

What’s the difference between 朝にコーヒーを飲みます and 朝はコーヒーを飲みます?

Changing に to は makes 朝 the topic: As for mornings, I drink coffee (implying evenings or nights are different). With 朝に, you’re simply stating when you drink coffee, without that contrast.

Can I use the plain form 飲む instead of 飲みます?

Yes. 飲みます is polite speech. In casual settings you’d say 朝にコーヒーを飲む. The meaning stays the same; you just adjust the formality.