Is the word japonesa the same in Brazilian and European Portuguese?

Yes

The word "japonesa" has the same meaning, spelling, and grammatical function in both Brazilian and Continental Portuguese. The only difference is pronunciation. In Brazilian Portuguese, vowels tend to be more open and the rhythm is more syllable-timed, meaning each syllable receives more distinct weight. In Continental Portuguese, unstressed vowels (such as the "e" in japonesa) are often more reduced, closed, or even nearly silent, making the word sound more "clipped" or "shortened" to a Brazilian ear.

Brazilian Portuguese Examples

1. Ela é japonesa. (She is Japanese.)
2. Eu adoro comida japonesa. (I love Japanese food.)
3. Minha amiga é japonesa. (My friend is Japanese.)
4. Essa técnica japonesa é muito útil. (This Japanese technique is very useful.)
5. A língua japonesa é fascinante. (The Japanese language is fascinating.)

Continental Portuguese Examples

1. Ela é japonesa. (She is Japanese.)
2. Eu adoro comida japonesa. (I love Japanese food.)
3. A minha amiga é japonesa. (My friend is Japanese.)
4. Esta técnica japonesa é muito útil. (This Japanese technique is very useful.)
5. A língua japonesa é fascinante. (The Japanese language is fascinating.)

(Note: In the Continental Portuguese examples, the use of the definite article "A" before the possessive "minha" is the natural way to express the idea, whereas Brazilians typically omit it.)