Learn Hardcore Japanese: watasi ha ii eiga wo mitai desu.

In this sentence, 私は marks 私 as the topic: we know the rest of the sentence is saying something about me. In English we just say I, but in Japanese you often set up the topic with 〜は.

Do I actually need to say 私 here? Can I just say いい映画を見たいです?

Yes, you can absolutely drop 私.

Japanese often omits pronouns when they are obvious from context. In a natural conversation, people would very often say:

いい映画を見たいです。
(I want to watch a good movie.)

The I is understood from context. The full 私はいい映画を見たいです。 is common in textbooks because it is clear and easy to analyze, but everyday speech frequently leaves 私 out.

What does the particle を do in 映画を見たいです?

を marks the direct object of a verb.

映画 = movie
映画を = (the) movie as the object of the action
見る = to watch / see
映画を見る = to watch a movie

So in this sentence, 映画を tells us that a movie is what is being (wanted to be) watched. The action 見る (watch) is applied to 映画 (movie).

I learned that 〜たい often uses が instead of を. Should it be いい映画が見たいです instead?

Both いい映画を見たいです and いい映画が見たいです are possible and natural.

General guideline:

Xが〜たい
Emphasizes what you want.
- いい映画が見たいです。
  = It’s a good movie that I want to see. (focus on the thing desired)
Xを〜たい
Treats the verb more like a normal transitive verb; a bit more neutral or action‑focused.
- いい映画を見たいです。
  = I want to watch a good movie. (focus slightly more on the action of watching)

In everyday conversation, both are used. Many textbooks teach that 〜たい prefers が, which is true as a grammatical rule, but を is also widespread, especially with verbs like 見る, 食べる, 飲む.

As a learner, it is safe and very natural to say either:

いい映画が見たいです。
いい映画を見たいです。

What exactly is 見たい? Is it a verb form? How is it made?

見たい is the desire form (the 〜たい form) of the verb 見る (to see / watch).

Formation:

Take the ます-stem of the verb:
- 見る → 見ます → 見 (ます-stem)
Add たい:
- 見 + たい = 見たい

Meaning: want to see / want to watch.

Grammatically, 〜たい behaves like an i-adjective, not like a verb:

見たい (want to see)
見たくない (do not want to see)
見たかった (wanted to see)
見たくなかった (did not want to see)

One important point: 〜たい strongly expresses the speaker’s own desire. For other people’s desires, Japanese often avoids directly using 〜たい and instead uses patterns like:

彼は映画を見たがっています。
= He seems to want to watch a movie.

Why is です added after 見たい? Isn’t 見たい already a complete form?

見たい by itself is a complete predicate in the plain (informal) style:

いい映画を見たい。
= I want to watch a good movie. (casual)

However, in polite Japanese, you often add です to the end of i-adjectives (and 〜たい acts like an i-adjective) to make the sentence polite:

見たいです = want to see (polite)
大きいです = is big (polite)

So:

いい映画を見たいです。
is simply the polite version of
いい映画を見たい。

The です does not change the core meaning; it just raises the politeness level.

How do I say I don’t want to watch a good movie or I wanted to watch a good movie using this pattern?

Because 見たい works like an i-adjective, you conjugate it like one.

Negative (don’t want to):

Plain: いい映画を見たくない。
Polite: いい映画を見たくないです。

Past (wanted to):

Plain: いい映画を見たかった。
Polite: いい映画を見たかったです。

Past negative (didn’t want to):

Plain: いい映画を見たくなかった。
Polite: いい映画を見たくなかったです。

The key change is たい → たくない / たかった / たくなかった.

Why is いい placed directly before 映画 with no particle? What is いい映画 grammatically?

いい is an i-adjective meaning good / nice.

When an i-adjective directly modifies a noun, it simply comes right before that noun, with no particle in between:

いい映画 = a good movie
大きい家 = a big house
新しい本 = a new book

So いい映画 is a single noun phrase: good movie.

A side note: historically, いい comes from よい, and in certain conjugations you will still see forms like よくない (not good). In modern spoken Japanese, いい and its conjugations like よくない / よかった are both common.

Can I change the word order, like 映画いいを見たいです or something similar?

No, that would be incorrect.

In Japanese, modifiers must come directly before the words they modify, and you cannot insert particles or other words between an adjective and its noun:

Correct: いい映画を見たいです。
(いい directly before 映画)
Incorrect: 映画いいを見たいです。
Incorrect: いいを映画見たいです。

The basic order here is:

Topic: 私は
Adjective + noun (object): いい映画
Object marker: を
Predicate (verb in たい form + です): 見たいです

Word order in Japanese is somewhat flexible at a higher level (phrases can move), but the internal order [adjective] + [noun] is fixed.

How do I specifically say I want to watch that good movie instead of a good movie?

To point to a specific movie, use a demonstrative like あの / その / この:

あの映画を見たいです。
= I want to watch that movie (over there).
その映画を見たいです。
= I want to watch that movie (you mentioned / you have).
この映画を見たいです。
= I want to watch this movie.

If you really want to keep good in there and still be specific, you could say:

あのいい映画を見たいです。
そのいい映画を見たいです。

But in practice, if both speakers already know which specific good movie is being discussed, people usually just say あの映画 / その映画 / この映画 and leave out いい. The good part is understood from context.

In contrast, いい映画を見たいです。 normally means I want to watch some good movie (not a specific one).

Can I drop を and just say いい映画見たいです in casual conversation?

In casual spoken Japanese, people often drop を (and sometimes other particles) when the meaning is clear:

いい映画見たい。
(very natural in speech)

However:

In writing and in learner Japanese, it is better to keep を.
In polite speech, it is also safer and more natural for learners to keep particles:
- いい映画を見たいです。 ✅ (recommended)
- いい映画見たいです。 sounds more casual; it can occur, but feels looser.

So yes, you will hear いい映画見たい, but as a learner, using いい映画を見たいです is clearer and always correct.

Is 私はいい映画を見たいです。 natural in real life, or is it just a textbook sentence?

It is grammatically correct and can be used in real life, especially in polite situations.

However, in everyday conversation, people often make it shorter and more natural by:

Dropping 私 if it’s obvious
Sometimes using が with 〜たい
Sometimes adding a sentence-ending particle for nuance

Examples of very natural alternatives:

いい映画が見たいな。
= I feel like watching a good movie.
なんかいい映画見たい。
= I kinda want to watch some good movie.
Polite but more likely: なんかいい映画を見たいです。

So:

私はいい映画を見たいです。
→ Perfectly correct, slightly textbook-like because of explicit 私は.
いい映画を見たいです。
→ Natural, polite, and commonly used.