YOU SAID:

I'm so fast try and catch me when I'm outside in the grass

INTO JAPANESE

私は草が茂って外にいるとき私はとても速く試みそして私を捕まえます

BACK INTO ENGLISH

I try very fast and catch me when I am grass and out there

INTO JAPANESE

私は草が茂っていてそこにいるとき、私は非常に速く試み、私を捕まえます

BACK INTO ENGLISH

When I am grass and there, I try very fast and catch me.

INTO JAPANESE

私が芝生だとそこにいるとき、私は非常に速くして私を捕まえます。

BACK INTO ENGLISH

When I'm in the lawn, I get very fast and catch me.

INTO JAPANESE

私が芝生にいるとき、私は非常に速くなって私を捕まえる。

BACK INTO ENGLISH

When I am on the lawn, I get very fast and catch me.

INTO JAPANESE

私が芝生の上にいるとき、私はとても速くなって私を捕まえる。

BACK INTO ENGLISH

When I am on the lawn, I get very fast and catch me.