YOU SAID:

The sister went to the store, came back, and ate tuna.

INTO JAPANESE

妹は店に行き、戻ってきて、マグロを食べました。

BACK INTO ENGLISH

My sister went to the store, came back and ate tuna.

INTO JAPANESE

私の妹は店に行き、戻ってきてマグロを食べました。

BACK INTO ENGLISH

My sister went to the store, came back and ate tuna.