Learn Hardcore Finnish: Tässä on kyse vain pienestä asiasta.

Kyse is historically a noun meaning something like “question, matter, issue”, but in modern Finnish it is used almost only in fixed expressions, especially:

olla kyse jostakin – to be about something, to concern something
olla kyseessä – to be at issue / to be the thing in question

In your sentence, on kyse (from olla) is the verb phrase, and kyse is part of that fixed expression, not a normal “free” noun.

You generally don’t use kyse like a regular noun in everyday modern language (you don’t say things like “tämä kyse”).

Why is asiasta not just asia? What case is asiasta, and why is it used here?

Asiasta is in the elative case (ending -sta/-stä), which often corresponds to English “from” or “about”.

The expression olla kyse jostakin always requires its complement in the elative:

Kyse on rahasta. – It’s about money.
Kyse ei ole sinusta. – It’s not about you.
Tässä on kyse vain pienestä asiasta. – This is only about a small matter.

So asiasta (“from/about the matter”) is required by the verb phrase olla kyse jostakin. You cannot say olla kyse pieni asia in nominative; it must be pienestä asiasta in elative.

Why does pienestä also end in -stä? Does it have to match asiasta?

Yes. In Finnish, adjectives agree with the noun they describe in:

case
number
and, when relevant, sometimes in other features too

Here:

asia → asiasta (elative singular)
pieni (small) → pienestä (elative singular)

So:

pieni asia – a small matter
pienestä asiasta – about a small matter

Because asiasta is elative singular, pieni must also be put in elative singular: pienestä.

Could I say Tässä on vain pieni asia instead of Tässä on kyse vain pienestä asiasta? What is the difference?

You can say Tässä on vain pieni asia, but it has a different nuance.

Tässä on vain pieni asia.
– more literally: “Here there is only a small thing.” / “This is just a small thing.”
– It sounds like you’re downplaying the thing itself that’s present or being discussed.
Tässä on kyse vain pienestä asiasta.
– “What we’re dealing with here is only a small matter.”
– This focuses more on the issue at hand, the subject under discussion, not a physical thing.

The version with kyse is more abstract and “discussion-like,” and is very common in spoken and written Finnish when talking about issues, topics, problems, questions.

What is the role of tässä here? Why tässä and not tästä?

Tässä is an adverb meaning “here / in this (situation)”.

In this sentence it points to the current situation or context:

Tässä on kyse vain pienestä asiasta.
≈ In this situation, what we’re dealing with is only a small matter.

Tästä would be the elative form of tämä (from/about this), and it works a bit differently. For example:

Tästä on kyse. – This is what it’s about.
Tästä asiasta on kyse. – It’s this matter that is at issue.

So:

Tässä on kyse… = “In this context, the issue is…”
Tästä on kyse… = “This (thing) is what it’s about.”

Your sentence uses tässä to set the general situation: “here / in this case”.

What does vain mean here, and can it be replaced with vaan?

In this sentence, vain means “only, just, merely”:

vain pienestä asiasta – only a small matter / just a small matter

You cannot replace vain with vaan here in standard Finnish:

vain = only
vaan = but / rather (as a conjunction), e.g.
- Ei iso, vaan pieni. – Not big, but small.

In some spoken dialects, vain and vaan can sound similar or be mixed, but in written standard language they are different words with different functions. So you must use vain in this sentence.

How flexible is the word order in Tässä on kyse vain pienestä asiasta? What other natural orders are possible?

Finnish word order is fairly flexible, mainly used to change emphasis. Some natural variants are:

Tässä on kyse vain pienestä asiasta.
– neutral, emphasizes the whole situation: Here, it’s only a small matter.
Kyse on vain pienestä asiasta.
– very common; focuses directly on what the issue is.
Vain pienestä asiasta on kyse.
– emphasizes “only a small matter” (contrastive, e.g. “not something bigger”).

All of these are natural.

Something like “Kyse on vain pienestä asiasta tässä” is grammatically possible but sounds a bit clumsy or marked; tässä is usually placed at the beginning in this type of sentence.

Why is the English translation often given as “This is only a small matter” instead of something closer to the literal structure “Here is a question of only a small matter”?

Because olla kyse jostakin is a fixed idiom, and translating it too literally sounds unnatural in English.

Literal-ish breakdown:

Tässä – here / in this (situation)
on – is
kyse – a question/matter (in idiomatic sense)
vain pienestä asiasta – about only a small matter

Natural English tries to match usage, not word-for-word form, so:

Tässä on kyse vain pienestä asiasta.
→ “This is only a small matter.”
→ or “We’re only dealing with a small matter here.”

These better capture how a native speaker would phrase the same idea, even though the literal structure looks different.

How could I express the same idea without using kyse?

You can avoid kyse and say, for example:

Tämä on vain pieni asia. – This is only a small thing/matter.
Se on vain pieni asia. – It’s only a small matter.
Tämä on ihan pikku juttu. (more colloquial) – This is just a little thing.

These lack the explicit “about / at issue” sense of olla kyse jostakin, but in context they often express the same practical meaning: downplaying the importance of the thing.

What other common expressions with kyse should I know that are related to this structure?

Useful related expressions:

Olla kyse jostakin – to be about something, to concern something
- Kyse on ajasta, ei rahasta. – It’s about time, not money.
Olla kyseessä – similar idea but used a bit differently:
- Kyseessä on vakava ongelma. – This is a serious problem. / We’re dealing with a serious problem.
Mistähän tässä on oikein kyse? – What on earth is going on here? / What is this really about?
Tästä on kyse: – This is what it’s about: (often followed by an explanation)

Your sentence Tässä on kyse vain pienestä asiasta fits right into this family of expressions.