YOU SAID:

A cat is sooo fat that i can hide behind him

INTO JAPANESE

猫は太っているので、後ろに隠れることができます

BACK INTO ENGLISH

Cats are fat so you can hide behind them

INTO JAPANESE

猫は太いので後ろに隠れることができる

BACK INTO ENGLISH

Cats are so thick that they can hide behind them.

INTO JAPANESE

猫はとても太いので、後ろに隠れることができる。

BACK INTO ENGLISH

The cat is so thick that he can hide behind it.

INTO JAPANESE

その猫はとても太いので、その猫の後ろに隠れることができる。

BACK INTO ENGLISH

The cat is so thick that he can hide behind it.