Learn Hardcore Japanese: zimoto no siten ha sudeni aite iru kara, sugu ikeru. - The local branch is already open, so we can go right away.

の links a modifier to a noun. Here it makes 地元 (local/one’s home area) modify 支店 (branch), giving “the local branch.” It’s attributive, not strict possession: think “branch in/for the local area.”

Why is は used after 支店 instead of が?

は marks the topic: “As for the local branch…” It sets up what you’re talking about, often with a contrastive feel (e.g., compared to other branches). Using が (地元の支店がすでに開いているから…) presents “the local branch is already open” as new/neutral information and focuses on that fact. Both are grammatically fine; nuance differs.

What’s the difference between すでに and もう?

Both can mean “already,” but:

すでに is a bit formal/written.
もう is common in conversation. Only もう naturally means “no longer” with negatives (e.g., もう開いていない = “it’s no longer open”). すでに開いていない sounds odd unless you mean “it was already not open” in a specific time frame.

Why is it 開いている and not 開く?

〜ている often expresses a resulting state: 開いている = “is open (now).” 開く is the event “to open.” 店が開いた = “The store opened.” After that event, its state is 店が開いている.

What’s the difference between 開いている and 開けている／開けてある?

開いている uses the intransitive verb and describes a state: “(something) is open.” For shops/doors, this is the default state description.
開けている uses the transitive verb: “(someone) is opening/keeping (something) open,” focusing on the actor’s action.
開けてある means “(someone) has opened it and left it that way (on purpose).” Common for doors/windows; less natural for a shop’s being open for business.

Can I say 空いている instead of 開いている for a shop?

In standard usage, use:

開いている for “open for business.”
空いている for “not crowded / available” (seats, time slots), e.g., 席が空いている. Some people colloquially say 店が空いている, but in careful speech/writing prefer 店が開いている for “the shop is open.”

What does から do here, and how is it different from ので?

から gives a reason: “because/since.” ので also means “because,” but is a bit softer/formal. Either is fine:

…開いているから、すぐ行ける。 (neutral/casual)
…開いているので、すぐ行けます。 (softer/more polite) In conversation you can even end with the reason alone: …開いているから。 (“Since it’s open (so…).”)

Who is the subject of 行ける? It isn’t stated.

Japanese often omits obvious subjects. Here it’s “I/we/you” depending on context. You can add one if needed:

私はすぐ行ける。 (I can go right away.)
私たちはすぐ行ける。 (We can go right away.)

Does すぐ mean “immediately,” “soon,” or “quickly” here?

すぐ can mean “right away/immediately” or “in a short time/with little delay.” In this sentence—paired with “already open”—it most naturally means “right away.” If you want to emphasize travel speed or short distance, you can clarify with すぐ着ける, 近いからすぐ行ける, or use すぐに for emphasis: すぐに行ける.

Is すぐに better than すぐ, and is に required?

に is optional. すぐ and すぐに are both correct; すぐに can sound a touch more explicit or formal. Meaning is the same in most contexts.

Why is there no destination particle like に／へ?

It’s inferable you’ll go “to the local branch.” Adding it is fine:

地元の支店にすでに開いているから、すぐ行ける。 (Ungrammatical: the に is attached to the wrong noun)
Correct: 地元の支店はすでに開いているから、（そこに）すぐ行ける。
Or make it explicit: 地元の支店にすぐ行ける。

How would I say this more politely?

For neutral-polite style:

地元の支店はもう開いていますので、すぐ行けます。
地元の支店はすでに開いているので、すぐ行けます。

Could I use なら instead of から?

Yes, but nuance changes:

地元の支店なら、すぐ行ける。 = “If it’s the local branch (as the option), we can go right away.” (なら sets up a condition/contrast.) You can combine reasons too: 地元の支店なら、すでに開いているからすぐ行ける。

Is 行ける the same as 行くことができる? Any other meanings?

They both mean “can go,” but 行ける (potential form) is natural and concise in speech; 行くことができる is longer/more formal or explanatory. Note 行ける can also mean “it’s doable/OK” (e.g., それ、行ける？ = “Think that’ll work?”), but here it clearly means physical going.

What’s the nuance of 地元 vs 近所 vs 最寄り?

地元: your home area/local region; carries an identity/affiliation nuance (“our local”).
近所: the neighborhood/nearby area.
最寄り: “nearest/closest” (often as 最寄りの支店 = “the nearest branch”). Use according to what you want to emphasize.

What’s the difference between 支店, 店舗, and 支社?

支店: a branch (often of a bank/retail chain) that serves customers.
店舗: a store/outlet (the shop itself).
支社: a branch office (organizational unit, typically not a retail storefront).