Learn Hardcore Japanese: natu no asa no sanpo ha kimoti ii desu. - Taking a walk on a summer morning feels good.

Each の connects the noun before it to the noun after it, building a bigger noun phrase step by step. This “noun + の + noun” chaining is extremely common in Japanese.

Is 夏の朝の散歩 all one big unit? How should I think about it?

Yes, 夏の朝の散歩 functions as one noun phrase, the topic of the sentence.

Structure:

夏 = summer
の = of
朝 = morning
の = of
散歩 = walk

So conceptually: [ (summer) の (morning) の (walk) ] → “(the) walk in the summer morning.”
Japanese likes to pack descriptive information in front of the main noun like this, rather than using separate prepositional phrases as in English.

Why is the particle は after 散歩 instead of が? What does it mean here?

は marks the topic, what the sentence is “about.”
In 夏の朝の散歩は気持ちいいです, you can read it as:

“As for a walk on a summer morning, it is pleasant.”

If you used が instead (夏の朝の散歩が気持ちいいです), it would sound more like you’re specifying exactly what is pleasant (as the grammatical subject), possibly in contrast to something else. For a general statement like “Summer morning walks are pleasant,” は is more natural, because you’re presenting it as a broad topic or general truth.

Why is there no verb like “to take” (散歩する) in this sentence?

Japanese often uses “noun + は + adjective” to say “X is [adjective]” without any verb like “do” or “take.”

夏の朝の散歩は気持ちいいです。
Literally: “As for summer-morning walks, (they) are pleasant.”

English tends to say “Taking a walk on a summer morning is pleasant,” so we add a verb. Japanese is fine with simply saying the walk itself “is pleasant,” and the act is understood from context.

What is the difference between 気持ちいい, 気持ちがいい, and 気持ちのいい?

They are closely related but used in slightly different ways:

気持ちがいい
- More “textbook standard.”
- Literally: “The feeling is good.”
- Used as a predicate:
  - 今日は風が気持ちがいい。
    “The breeze feels good today.”
気持ちいい
- Colloquial, sounds a bit more casual/smooth.
- Grammatically, it’s like 気持ちがいい with the が dropped in fast speech.
- Very common in conversation:
  - 夏の朝の散歩は気持ちいい。
- Perfectly natural; you’ll hear it all the time.
気持ちのいい
- Used before a noun, to describe it:
  - 気持ちのいい風 = “a pleasant-feeling breeze”
  - 気持ちのいい散歩 = “a pleasant walk”

In your sentence, 気持ちいいです is a predicate (“is pleasant”), so 気持ちいい or 気持ちがいい both work, with 気持ちいい sounding more conversational.

Why is いい used instead of よい? Are they different?

よい and いい are basically the same adjective; いい is the more common spoken form.

Dictionary/plain form is often shown as よい, but in real conversation people almost always say いい.
Conjugations in polite forms are based on よい historically, but いい is accepted and very common:
- Past: よかった / いいです → いいです and よかった are both standard in modern Japanese, though many learners first learn よかった.

In 気持ちいいです, using いい is natural and typical speech. 気持ちよいです is correct but sounds a bit more formal or literary.

If いい is an adjective, why do we still add です? Isn’t that redundant?

いい is indeed an い-adjective, and grammatically it doesn’t require です to form a sentence:

気持ちいい。= “(It) feels good.”

Adding です makes the sentence polite:

気持ちいいです。= “It feels good.” (polite)

So:

Plain/casual: 夏の朝の散歩は気持ちいい。
Polite: 夏の朝の散歩は気持ちいいです。

です does not change the meaning here; it softens the tone.

Can I make this sentence more casual or more formal? What variations are natural?

Yes. Here are some common variations:

Polite (as given):
夏の朝の散歩は気持ちいいです。
Casual:
夏の朝の散歩は気持ちいい。
→ Drop です.
A bit more “standard” / textbook:
夏の朝の散歩は気持ちがいいです。
Very casual, spoken:
夏の朝の散歩って気持ちいいね。
- って is a casual topic marker.
- ね adds “right?” / seeking agreement.

All of these are grammatical; the choice depends on the level of politeness and the situation.

Could I change the order, like 朝の夏の散歩 instead of 夏の朝の散歩?

You generally would not say 朝の夏の散歩. It sounds unnatural or confusing.

In Japanese, modifiers usually go from bigger context → closer detail in a way that feels natural to native speakers. For something like this, 夏の朝の散歩 is the standard flow:

First: what season (夏の)
Then: what time of day (朝の)
Finally: what activity (散歩)

Changing the order can sound odd or imply a different nuance that often doesn’t match what you want. So stick with 夏の朝の散歩.

Why is there no particle after 朝 (as in 夏の朝の散歩)? Is anything being omitted?

Nothing is omitted; の is directly connecting each noun:

夏の朝の散歩

Think of it as a chain:

夏の朝 = “summer morning”
(夏の朝) の散歩 = “(summer-morning) walk”

You don’t put another particle like は or が after 朝 here because 朝 is in the middle of a noun phrase, not the topic or subject on its own. It’s just one step in the chain of modifiers leading to 散歩.

Who is actually feeling good in 気持ちいいです? The walk or the person?

Grammatically, the sentence is saying “(Summer morning walks) are pleasant.” But in natural interpretation, it implies:

“When I (or people in general) take a walk on a summer morning, it feels good.”

Japanese often omits the experiencer (the person who feels something) when it’s obvious:

夏の朝の散歩は気持ちいいです。
→ The walk is described as 気持ちいい, but it’s understood that the person doing the walk experiences that pleasant feeling.

So the sentence is about the general experience, not about the walk having “feelings” in a literal sense.