YOU SAID:

three corners have my hat

INTO JAPANESE

三隅には帽子があります

BACK INTO ENGLISH

There are hats in the three corners

INTO JAPANESE

三隅に帽子があります

BACK INTO ENGLISH

There is a hat in the corner

INTO JAPANESE

角に帽子があります

BACK INTO ENGLISH

There is a hat at the corner

INTO JAPANESE

角に帽子があります

BACK INTO ENGLISH

There is a hat at the corner