Learn Hardcore Japanese: zyugyougo ni tomodati to issyo ni syokudou de koohii wo nomimasu. - After class, I drink coffee with a friend in the cafeteria.

Here に is a time marker: it marks the point in time when something happens.
授業後 by itself means “after class” as a noun-like time expression. Adding に turns it into “at/after that time”.

Is it necessary?

In many everyday sentences, time expressions can drop に, especially when the meaning is clear.
So both of these are possible and natural:
- 授業後に友達と一緒に…
- 授業後友達と一緒に… (slightly more casual / “lighter”)

Using に is very safe and slightly more explicit, especially for learners.

What’s the difference between 授業後 and 授業の後? Can I use both?

Both mean “after class / after the lesson”, but:

授業後
- More compact, slightly more written/neutral.
- Literally “class-after” (a Sino-Japanese compound).
- Common in schedules, announcements, textbooks, etc.
授業の後
- More “plain Japanese,” feels a bit more conversational/explicit.
- Literally “the after of class.”

In this sentence you could also say:

授業の後に友達と一緒に食堂でコーヒーを飲みます。

Natural and correct. For everyday speech, 授業の後(に) might even feel more typical; 授業後(に) sounds a bit more formal/concise.

Why do we have both 友達と and 一緒に? Aren’t they basically the same?

They overlap in meaning but are not identical:

友達と = “with my friend(s)” (literally: “with friend”).
一緒に = “together”.

When you combine them:

友達と一緒に = “together with my friend(s)”.

You can say either on its own:

友達と食堂でコーヒーを飲みます。
→ “I drink coffee in the cafeteria with my friend(s).”
一緒に食堂でコーヒーを飲みます。
→ “I drink coffee in the cafeteria together (with someone).”
(The “someone” is usually clear from context.)

But 友達と一緒に is very natural Japanese and emphasizes both the companion and the idea of doing it together. It’s not “wrong” redundancy; it’s just normal phrasing.

Why does 一緒 take に (as in 一緒に)? What is に doing there?

In 一緒に, the に turns 一緒 (“together”) into an adverbial phrase meaning “together (with)”.

Think of:
- 一緒 = “together” (as a noun-like word)
- 一緒に = “in a together way” → “together” modifying the verb.

You almost always use 一緒 as 一緒に + verb:

一緒に行きます – “(I) go together (with you).”
一緒に食べる – “(We) eat together.”

So in practice, just memorize 一緒に as the set expression “together (with ~)”.

Why is で used after 食堂 instead of に?

で marks the location where an action takes place.

食堂でコーヒーを飲みます。
→ “I drink coffee in the cafeteria.” (the cafeteria is the place where the drinking happens)

Compare:

で: place of action
- 図書館で勉強します。 – “I study in the library.”
に: place of existence, destination, or arrival point
- 図書館に行きます。 – “I go to the library.”
- 図書館にいます。 – “I am in the library.”

Here, drinking is an action happening at the cafeteria, so 食堂で is correct.

Where is the subject “I”? How do we know who is drinking the coffee?

Japanese often omits the subject when it’s clear from context.

飲みます by itself doesn’t say who drinks.
In an actual conversation, the listener already knows whether you’re talking about yourself, your friend, “we,” etc.

In a typical textbook context, this sentence is interpreted as:

(私は) 授業後に友達と一緒に食堂でコーヒーを飲みます。
→ “I drink coffee in the cafeteria with my friend(s) after class.”

If context made it clear you were describing someone else, it could be:

(田中さんは) 授業後に…コーヒーを飲みます。 – “Tanaka drinks…”

So the subject is understood from context, not explicitly stated.

Does 飲みます mean “drink” or “will drink”? How is tense expressed here?

Japanese -ます (non-past polite) covers both present and future:

飲みます can be:
- “drink / do drink / usually drink”
- or “will drink / am going to drink”

The exact nuance comes from context and sometimes time words:

毎日コーヒーを飲みます。 – “I drink coffee every day.” (habitual)
あとでコーヒーを飲みます。 – “I’ll drink coffee later.” (future)

In your sentence:

授業後に…コーヒーを飲みます。
→ Usually understood as future or habitual:
- “I will drink coffee after class (today).”
- or “I usually drink coffee after class.”

Can I change the word order, for example: 友達と授業後に食堂でコーヒーを飲みます? How flexible is the word order?

Japanese word order is fairly flexible, as long as:

The verb comes at the end.
The particles stay attached to the words they belong to.

Your example:

友達と授業後に食堂でコーヒーを飲みます。

is grammatically fine and understandable. However, some orders sound more natural:

Very natural:
- 授業後に友達と一緒に食堂でコーヒーを飲みます。
Also okay:
- 友達と一緒に授業後に食堂でコーヒーを飲みます。 (slightly unusual emphasis)
- 授業後に食堂で友達と一緒にコーヒーを飲みます。

As a learner, it’s safe to keep to the textbook-like order:

[Time] + [With whom / manner] + [Place] + [Object] + [Verb]
授業後に + 友達と一緒に + 食堂で + コーヒーを + 飲みます。

Is 友達 singular or plural? How do I say “a friend” vs “friends”?

友達 (ともだち) itself does not mark singular or plural. It just means “friend / friends”.

The number is inferred from context, but you can clarify:

“a friend” / “one friend”
- 友達と often just means “with a friend” in many contexts.
- To be explicit, you can say 友達一人と (“with one friend”), but this is less common in casual talk unless the number matters.
“friends” (plural)
- Context alone often implies this.
- Or you can say:
  - 友達たちと – “with my friends” (but sounds a bit childish / emphatic)
  - 友達みんなと – “with all my friends”
  - 友達数人と – “with several friends”

In everyday speech, 友達とコーヒーを飲みます is usually understood as “I drink coffee with a friend or some friends,” depending on the situation.

Is the particle を after コーヒー compulsory? I heard particles are sometimes dropped.

In correct standard Japanese, you should include を:

コーヒーを飲みます。 – “(I) drink coffee.”

を marks コーヒー as the direct object of the verb.

Particles can be dropped in very casual speech, especially が, は, を, but:

That’s mainly in spoken Japanese among natives.
As a learner, you should keep the particles until you have a very good feel for when dropping them still sounds natural and not confusing.

So in writing and polite speech, コーヒーを飲みます is the correct and recommended form.

Can I replace 食堂 with words like カフェ or レストラン? What’s the nuance difference?

Yes, you can replace 食堂 with other location words:

食堂 – usually a cafeteria / dining hall
- Common in schools, companies, dormitories, hospitals, etc.
- Often a more functional, not-so-fancy place.
カフェ – a café
- Coffee-focused place, more like Western cafés or coffee shops.
レストラン – a restaurant
- Usually a sit-down place, more for full meals.

Examples:

授業後に友達と一緒にカフェでコーヒーを飲みます。
→ “I drink coffee at a café with my friend(s) after class.”
授業後に友達と一緒にレストランでコーヒーを飲みます。
→ “I drink coffee at a restaurant with my friend(s) after class.”

The grammar is the same; only the type of place changes.

How would this sentence look in casual (plain) speech?

The polite verb 飲みます becomes its plain form 飲む. Everything else can stay the same:

授業後に友達と一緒に食堂でコーヒーを飲む。

This is how you might speak to close friends or family. You can also optionally drop some parts in casual conversation if the context is clear, for example:

授業後、友達と食堂でコーヒー飲む。
(Dropped に, 一緒, and を – very casual, but natural among natives.)

For now, it’s good to master the polite form first:

授業後に友達と一緒に食堂でコーヒーを飲みます。