Yes, the sentence does require an article before the word **Japanese**. It's because we don't talk about **team**. 

We talk about **a team** or **the team**. The choice would depend on whether the writer thought that the intended audience were familiar with Samurai Blue. If **yes**, then use the definite article. If **no**, the indefinite. If unsure, use either one.

And the expression is NOT **win to the round**. It is **win through to the round** or **got through to the round**.

Finally, NOT **the round of 16**, just **to round 16** (or possibly the quarter finals etc, depending on how many rounds there were).

https://www.merriam-webster.com/dictionary/win%20through