YOU SAID:

I gave my cousin my old AirPods case.

INTO JAPANESE

私はいとこに私の古いAirPodsケースを与えました。

BACK INTO ENGLISH

I gave my old AirPods case to my cousin.

INTO JAPANESE

私は私のいとこに私の古いAirPodsケースを与えました。

BACK INTO ENGLISH

I gave my old AirPods case to my cousin.