Breakdown of imouto wa gooru no mae de tomatte shimatte, ruuru o mou ichido sensei ni kiita.
Questions & Answers about imouto wa gooru no mae de tomatte shimatte, ruuru o mou ichido sensei ni kiita.
は marks 妹 as the topic of the sentence: as for my younger sister...
That means the sentence is talking about what happened to her. Using が would put more focus on 妹 as the grammatical subject in a more neutral or contrastive way.
So:
- 妹は = as for my younger sister...
- 妹が = my younger sister (is the one who)...
In this sentence, は sounds very natural because the speaker is simply telling what she did next.
