Learn Hardcore Japanese: watasi to tomodati ha sorezore hon to zassi wo kaimasita. - My friend and I each bought a book and a magazine.

In 私と友達は, the particle と simply links two nouns, so it means “and.” Here it joins 私 (“I”) and 友達 (“friend”) into one compound topic: “my friend and I.” Note that と can also mean “with” in some contexts (e.g. 友達と遊ぶ “play with a friend”), but when it sits between two nouns at the start of a sentence, it most often functions as “and.”

Why is は attached only once at the end of 私と友達? Can we mark 私 and 友達 with は separately?

Japanese lets you attach は to an entire noun phrase—even if it contains multiple nouns—so 私と友達は marks “my friend and I” as the single topic. If you marked each noun separately (e.g. 私は… 友達は…), you’d create two distinct topical statements, which changes the structure:
• 私は本を買いました。
• 友達は雑誌を買いました。
Here you’d be making two sentences or clauses. Using 私と友達は keeps them together as one topic sharing the same verb.

What is the function of それぞれ in this sentence?

それぞれ means “respectively” or “each.” It indicates that the members of the topic (私 and 友達) independently performed the action on different but parallel objects. In English: “My friend and I each bought a book and a magazine.” Grammatically, それぞれ acts adverbially, modifying 買いました to express distribution across the subjects.

Why is the object marker を used only once for 本 and 雑誌?

When you have multiple direct objects joined by と, you need only one を at the end of the list. Here 本 and 雑誌 are both objects of 買いました, so 本と雑誌を買いました is sufficient. If you wanted to treat them totally separately, you could say 本を買って、雑誌を買いました, but for a simple list joined by と, one を covers them all.

What role does the second と play between 本 and 雑誌?

That と is the same “and” particle that connects nouns. It simply links 本 (“book”) and 雑誌 (“magazine”) into the compound object 本と雑誌 (“a book and a magazine”).

Could we use ずつ instead of それぞれ here? What’s the difference?

You can express “each” with ずつ, but it typically attaches to counters or numeral phrases (e.g. 一冊ずつ “one copy each”). A natural alternative would be:
• 私と友達は本と雑誌を一冊ずつ買いました。
This explicitly says “we each bought one book and one magazine.”
それぞれ is more flexible—an adverb—so it works without changing other parts of speech.

Is the word order in this sentence fixed? Could we move それぞれ or 本と雑誌を elsewhere?

Japanese word order is fairly flexible thanks to particles. For example, you could say:
• 私と友達は本と雑誌をそれぞれ買いました。
• 本と雑誌をそれぞれ、私と友達は買いました。
All of these are grammatical, though subtle nuances in emphasis may shift. The most neutral order is topic → adverb → object → verb, as in the original.

What happens if we change それぞれ to それぞれの before 本と雑誌 (i.e. それぞれの本と雑誌を買いました)?

Turning それぞれ into the adjective それぞれの makes it modify 本と雑誌 (“each person’s book and magazine”), shifting the nuance:
• それぞれの本と雑誌を買いました。
This implies “(We) bought each one’s own book and magazine,” focusing on possession rather than distribution. It’s less common if your goal is simply “we each bought a book and a magazine.” For that, the adverbial それぞれ is clearer.