Learn Hardcore Japanese: sensei ga osusumesita sankousyo ha,hondana no itiban ue no dan ni simatte aru. - The reference book recommended by the teacher is stored on the top shelf of the bookshelf.

In Japanese relative clauses, the subject is most commonly marked with が, not は. Using は there would sound odd because は tends to mark the overall topic of the sentence, but here 先生 is just the subject inside a subordinate clause.

So:

先生がおすすめした参考書 = “the reference book that the teacher recommended” (natural)
先生はおすすめした参考書 = sounds ungrammatical in this role as a modifier

What does 先生がおすすめした参考書 as a whole mean grammatically?

It’s a noun phrase with a relative clause:

先生が – subject: “the teacher”
おすすめした – past form of おすすめする: “recommended”
参考書 – noun: “reference book / study guide”

So 先生がおすすめした directly modifies 参考書:

先生がおすすめした参考書
“the reference book (that) the teacher recommended”

There is no relative pronoun like “that” or “which” in Japanese; the clause just goes in front of the noun.

What is the role of は after 参考書?

In 参考書は、本棚の一番上の段にしまってある。:

参考書は marks 参考書 as the topic of the sentence.
The English equivalent is like starting with “As for the reference book (the teacher recommended), …”

So the structure is:

[先生がおすすめした参考書] は – “As for the reference book that my teacher recommended,”
本棚の一番上の段にしまってある。 – “it is put away on the top shelf of the bookcase.”

が in the relative clause marks the subject of that clause; は in the main clause marks the overall topic.

What’s the difference between おすすめする and 勧める?

Both can mean “to recommend,” but their nuances differ:

おすすめする
- Slightly more polite / neutral sounding
- Common in service situations: shops, ads, teachers, etc.
- Often used for products, choices, options
- e.g. 先生がおすすめした参考書 – “the study guide my teacher recommended”
勧める（すすめる）
- More direct “to urge someone to do something / take something”
- Frequently used when urging an action: drink, read, do, try
- e.g. 本を読むことを勧める – “recommend (urge) that someone read a book”

In many everyday sentences you can swap them, but おすすめした参考書 sounds like a natural, slightly polite way of saying “the recommended reference book.”

What exactly does 参考書 mean? Is it just “book”?

参考書（さんこうしょ） is not just any “book.” It specifically means:

“reference book,” “study guide,” “supplementary textbook”

Typically:

exam prep books
grammar guides
reference materials used alongside a main textbook

So 先生がおすすめした参考書 is something like:

“the study guide / reference book my teacher recommended,”
not just “a book my teacher recommended.”

How is 本棚の一番上の段 structured?

Breakdown:

本棚 – “bookshelf / bookcase”
本棚の – “of the bookshelf” / “on the bookshelf” (possessive/locative の)
一番上 – “the very top / the topmost”
の段 – “shelf level” (段 = “step / tier / shelf level”)

Put together:

本棚の一番上の段
= “the very top shelf of the bookcase”

Literally: “the shelf that is the very top of the bookshelf.”

Why is に used in 本棚の一番上の段にしまってある?

The particle に here marks the location where something ends up / is placed.

〜にしまう – to put something away in/at/on some place
本棚の一番上の段にしまう – “to put (it) away on the top shelf of the bookshelf”

Then 〜てある adds the idea that it’s now in that state (stored there). So:

本棚の一番上の段にしまってある。
= “(It) has been put away on the top shelf of the bookcase (and is there now).”

What does しまってある mean exactly, and why use しまう here?

しまってある is:

しまう (to put away, to stow, to put out of sight)
→ しまっ (te-form stem) + てある

So:

しまう – to put something away / store it
〜てある – “has been done (and the result remains now)”

しまってある therefore means:

“has been put away and is (now) in a stored/put-away state.”

It emphasizes both:

The completed action of putting it away, and
The current result (it is currently stored there).

What’s the nuance of 〜てある compared to 〜ている in this sentence?

Compare:

本棚の一番上の段にしまってある。
- Uses 〜てある
- Focuses on: “It has been put away and is (deliberately) in that state now.”
- Implies someone intentionally put it there.
本棚の一番上の段にしまっている。
- Uses 〜ている
- More like: “It is being kept/stored on the top shelf.”
- Describes the ongoing state, but doesn’t highlight the deliberate completed action as strongly.

In practice:

〜てある = result of a completed, intentional action is present
〜ている = current state or ongoing action

Here, しまってある nicely says: “Someone put it away, and that’s why it’s now on the top shelf.”

Is しまってある passive voice?

No. しまってある is not a passive form.

Passive of しまう would be something like しまわれる (“to be put away (by someone)”).
てある is a special construction: verb (transitive) + てある.

It expresses:

A resulting state of a deliberate action,
Without explicitly saying who did it.

So しまってある means:

“(It) has been put away and is in that state,”

not “(It) is put away (by someone)” in a passive-voice grammatical sense.

Could you rewrite the sentence in a more “English-like” word order to see the structure?

Original:

先生がおすすめした参考書は、本棚の一番上の段にしまってある。

Rough, structure-exposing English order:

“The reference book that the teacher recommended is (now) put away on the top shelf of the bookshelf.”

Japanese structure:

先生がおすすめした – relative clause: “that the teacher recommended”
参考書は – topic: “as for the reference book”
本棚の一番上の段に – place: “on the top shelf of the bookcase”
しまってある – predicate: “has been put away and is there now”

Can I drop 先生が and just say おすすめした参考書?

You can, but only if the context makes it totally clear who did the recommending.

おすすめした参考書は、本棚の一番上の段にしまってある。
Could mean: “The reference book (I / you / someone) recommended is on the top shelf.”

Without 先生が, the subject of おすすめした is left implicit. In the original sentence, 先生が is important because it tells us exactly who recommended it: “my/the teacher.”

Why is there a comma after は: 参考書は、本棚…? Is it necessary?

The comma is optional and is used mainly for readability and rhythm.

先生がおすすめした参考書は本棚の一番上の段にしまってある。 – grammatically fine
先生がおすすめした参考書は、本棚の一番上の段にしまってある。 – same meaning, easier to read

Writers often put a comma after the topic + は when the topic is long, like:

先生がおすすめした参考書は、
(long chunk) → comma helps visually separate the topic from the rest of the sentence.