Learn Hardcore Japanese: sofa no ue ni titi no uwagi ga oite atte, sukosi zyama desu. - My father's jacket has been left on the sofa, and it's a bit in the way.

The particle に by itself just marks a place or goal, without saying on top of / inside / under etc. Sometimes Xに can mean “on X” (e.g. いすに座る “sit on a chair”), but that’s because the verb 座る (“sit”) already implies how your body relates to the chair.

For a physical object resting on the surface of another object, Japanese usually specifies the relation with:

～の上に (on top of)
～の中に (inside)
～の下に (under), etc.

So ソファの上に父の上着が… is the natural way to say “My father’s jacket is on the sofa.”

What’s the nuance of 父 here? Why not お父さん?

父（ちち） is the standard, humble word for “my father” when talking about your own father to someone outside your family.

父 → “my father” (humble, used when talking to outsiders)
お父さん → “dad” / “father” (polite/honorific; used to address your father, or to talk about someone else’s father)

In this sentence:

父の上着 = “my father’s jacket”

If you said お父さんの上着, that would sound like you’re talking about someone else’s father (or addressing your own father directly), which doesn’t fit a neutral written example sentence. Using 父 matches a textbook-like, neutral style: the speaker is describing their own father to the listener.

What exactly does 上着（うわぎ） mean? How is it different from コート or ジャケット?

上着（うわぎ） is a general word for any outer garment worn on the upper body. It’s broad:

Jackets
Coats
Blazers
Hoodies
Cardigans
Anything you “put on over” other clothes on your upper body

コート tends to mean a coat (usually longer, for going outside).
ジャケット is a jacket (shorter, like suit jackets, casual jackets).

In many contexts, you could translate 父の上着 as either “my father’s jacket” or “my father’s coat,” depending on what feels more natural in English. Japanese here is deliberately non-specific.

Why does the sentence use が with 父の上着が and not は?

が is marking 父の上着 as the grammatical subject and also as new information being presented:

父の上着が置いてあって…
- “(There) is my father’s jacket placed (there)…”

If you used は:

父の上着はソファの上に置いてあって…
- This would make 父の上着 the topic, something already known or being contrasted with something else.

Nuance:

が: “There is my father’s jacket (on the sofa)” → neutral, introducing the fact.
は: “As for my father’s jacket, it’s (the one that’s) placed on the sofa…” → more contrastive or topical.

In a simple descriptive sentence like this, が is more natural because you’re just stating what’s there and what’s in the way.

What does 置いてあって mean exactly? How is it formed?

置いてあって comes from:

置く – “to put, to place”
置いてある – a set pattern: V-てある
- “has been put (and remains there)”
- Describes a resulting state created by someone’s intentional action
The て-form of 置いてある is 置いてあって:
- 置いてある → 置いてあって (to connect to the next clause)

So in the sentence:

父の上着が置いてあって、少しじゃまです。
≈ “My father’s jacket has been left (placed) there on the sofa, and it’s a bit in the way.”

Key points:

It’s not simply “is being put”; it’s “has been put and is sitting there now”.
The extra あって is from ある, not from repeating the verb; 置いてあって = “is in the state of having been placed.”

What is the grammar pattern ～てある, and why is it used here instead of ～ている?

～てある describes a state that is the result of someone’s intentional action. Structure:

transitive verb (object + を) in て-form + ある
ドアが開けてある。
“The door has been (deliberately) left open.”

Nuance differences:

～ている (e.g. 置いている)
- Can mean a continuing action or ongoing state, but doesn’t necessarily imply “on purpose / for a reason.”
- 上着がソファの上に置いている is actually unnatural; you’d say:
  - 上着がソファの上に置いてある。
～てある (e.g. 置いてある)
- “(Someone) has put it there, and it is in that placed state.”

In this sentence, 置いてあって implies:

Someone (probably the father) put the jacket there and left it, and now it’s just sitting there, causing it to be a bit of a nuisance. That sense of “left there” fits ～てある well.

In 少しじゃまです, what is actually “in the way”? Why isn’t it mentioned?

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

Here, the preceding clause mentions:

父の上着が置いてあって…

So the listener already knows the topic: the father’s jacket on the sofa. Therefore, in the next clause:

少しじゃまです。
Literally: “(It) is a little in the way.”

We naturally understand “it” = 父の上着 (the jacket).

In English, you need the pronoun “it,” but in Japanese:

Repeating 上着は少しじゃまです is possible, but feels heavier.
Just saying 少しじゃまです is natural and avoids repetition.

What does じゃま mean, and how is it used in sentences like this?

じゃま（邪魔） is a na-adjective / noun meaning:

“hindrance,” “obstruction,” “nuisance,” “in the way,” “disturbing.”

Common patterns:

じゃまです – “(it) is in the way / is a nuisance”
- ここに置くとじゃまです。 – “If you put it here, it’s in the way.”
じゃまになる – “to become an obstruction”
- 荷物が多いと、移動するときじゃまになります。
  “If you have a lot of luggage, it gets in the way when you move around.”
じゃまをする – “to disturb, to bother, to interrupt”
- 勉強のじゃまをしないで。 – “Don’t disturb my studying.”

In this sentence:

少しじゃまです。
= “It’s a bit in the way / kind of annoying (because it’s in the way).”

The nuance is physical obstruction more than emotional annoyance.

Why is 置いてあって in plain form but the sentence ends with polite です? Is that okay?

Yes, that’s standard Japanese.

The rule of thumb:

Only the final main verb / copula in the sentence needs to show politeness.
Verbs inside subordinate clauses (like those before て, から, ので, etc.) are usually in plain form, even in polite speech.

So:

ソファの上に父の上着が置いてあって、少しじゃまです。
- 置いてあって → plain form in a connecting clause
- です → polite form in the main clause

This balance is very natural: the sentence as a whole is polite because it ends in です, even though 置いてあって is plain.