Learn Hardcore Japanese: isogasii asa ni ha, yuka ga sukosi tirakatte ite mo ki ni sinaikoto ni site imasu. - On busy mornings I decide not to worry even if the floor is a bit messy.

The verb phrase is 散らかっている (to be messy / to be scattered).
散らかっている describes a state of something, not an action being done to something.
For verbs that describe a state or condition, the “thing that is in that state” is typically marked by が.

So:

床が散らかっている = the floor is messy (the floor is in the state of being scattered about).
Using を would not work here because 床 is not a direct object; the verb is not “to scatter the floor” but “to be scattered/messy”.
床は散らかっていても is grammatically possible, but:
- 床が just states a fact: “the floor is messy”.
- 床は would make “the floor” the topic, sometimes with a contrast nuance (e.g., “as for the floor, even if it’s messy…”). In this sentence, the neutral descriptive が is more natural.

What exactly does 散らかっていても mean, grammatically speaking?

散らかっていても is:

散らかる (to be scattered / to be messy) → 散らかっている (to be in a messy state)
散らかっている in te-form + も: 散らかっていても.

Breakdown:

散らかっていて = the te-form of 散らかっている, “being messy / in a messy state”.
も after the te-form has the meaning “even if / even though”.

So:

床が少し散らかっていても ≈ even if the floor is a little messy / even when the floor is a bit messy.

Nuance:

This is about the state of the floor at that time, not the action of someone “scattering” it.

Why is it 散らかっていても and not 散らかっても?

You could say 散らかっても, and people would understand, but there is a nuance difference:

散らかっている focuses on a resulting state: “(already) messy”.
散らかる (without ている) describes the action / event of becoming messy.

So:

床が少し散らかっていても:
- Emphasizes “even if the floor is a bit messy (in that state)”.
床が少し散らかっても:
- Can sound more like “even if the floor gets a bit messy (even if it becomes messy)”.

In this sentence, the speaker is talking about how they don’t mind the current state of the floor on busy mornings, so 散らかっていても (state) fits very naturally.

What does 気にしない mean here, and how is it different from 気になる?

気にする = to mind something / to worry about it / to care about it (in the sense of being bothered).
- 気にしない = not to mind / not to worry / not to let it bother you.
気になる = something catches your attention, worries you, or sticks in your mind.
- It’s more like “it bothers me” or “I’m curious / concerned about it”.

So:

床が少し散らかっていても気にしない:
- I don’t let it bother me even if the floor is a bit messy.
If you said 床が少し散らかっていると気になる, that would mean:
- When the floor is a little messy, it bothers me / it gets on my mind.

In this sentence, the idea is “I choose not to let it bother me,” so 気にしない fits perfectly.

What is the function of こと in 気にしないことにしています?

Here, こと is a nominalizer: it turns a verb phrase into a noun-like thing.

気にしない = “(to) not mind it”.
気にしないこと = “the act of not minding it / not caring about it” (treated as a “thing” or “policy”).

This then becomes the “thing” that is the object of 〜にする / 〜にしている:

〜ことにする = “to decide that ~ (will be the case / will be my policy)”.
So 気にしないことにする = to decide that I won’t mind it.

In the sentence, it’s 気にしないことにしています = I make it a rule not to mind it / I go with not caring about it (as an ongoing habit).

What does the pattern 〜ことにしている mean, exactly?

〜ことにしている is a very common pattern:

〜こと = nominalized clause (treating the verb phrase as a “thing”).
〜ことにする = “to decide to do ~ / to make it so that ~”.
〜ことにしている = progressive form of にする, and in this expression it usually means:
- “I have made it my habit (rule, policy) to ~ and I’m continuing that habit now.”

So in this sentence:

気にしないことにしています ≈
- I make it a rule not to care about it.
- I’ve decided (for myself) not to worry about it, and I live by that decision.

It’s not just a one-time decision; it implies an ongoing personal rule or habit.

What is the difference between 〜ことにする and 〜ことにしている?

They’re closely related but differ in time and aspect:

〜ことにする
- A (relatively) one-time decision at a particular moment.
- Example:
  - 今日は早く寝ることにする。
    - I’ll decide to go to bed early today / I’ll go to bed early today.
〜ことにしている
- A decision that has become an ongoing habit or policy.
- Example:
  - 平日はお酒を飲まないことにしている。
    - I make it a rule not to drink on weekdays / I don’t drink on weekdays (as a standing rule).

In your sentence:

気にしないことにしています:
- The speaker is saying they have an established, continuing policy of not minding a slightly messy floor on busy mornings.

Why is it しています and not just します in 気にしないことにしています?

しています here is the te-iru form of する, and in this pattern it expresses an ongoing state based on a past decision.

Compare:

気にしないことにします。
- I will decide not to mind it (I’m making that decision now).
気にしないことにしています。
- I have made it my rule not to mind it.
- Implies this is already your current habitual policy, not just a fresh decision.

So 〜ことにしています is the standard way to say:

I (nowadays) do X as a rule / It is my habit/policy to do X.

How does 忙しい work with 朝 here? Is it just “busy morning”?

Yes. 忙しい is an i-adjective, and it directly modifies the noun 朝:

忙しい = busy.
朝 = morning.
忙しい朝 = busy morning.

This is exactly like English adjective + noun:

楽しい映画 = fun movie.
長い時間 = long time.
忙しい朝 = busy morning.

Then the phrase becomes 忙しい朝に(は) = on busy mornings / when mornings are busy.

Who is the subject of the sentence? Why is “I” not written?

In Japanese, the subject (like 私 = I) is often omitted when it is clear from context.

The sentence:

忙しい朝には、床が少し散らかっていても気にしないことにしています。

Literally:

On busy mornings, even if the floor is a little messy, (I) make it a rule not to mind it.

私 is not written, but:

The verb しています with 〜ことにしている is very commonly used to describe one’s own habits or personal rules.
In most natural contexts, listeners will understand it as “I”.

If you really wanted to be explicit:

私は忙しい朝には、床が少し散らかっていても気にしないことにしています。

Is this sentence polite, casual, or formal?

The sentence is in polite (です／ます) style because of しています.

Casual version:
- 忙しい朝には、床が少し散らかっていても気にしないことにしてる。
More formal/written version (minor tweak):
- 忙しい朝には、床が少し散らかっていても気にしないことにしています。 (already sounds fine in many formal-ish contexts)

So:

It’s polite but natural/conversational, suitable for talking to someone you’re not too close to, in everyday situations.