YOU SAID:

my friend killed my brother's dog's cousin's sister's neighbour and ate him for breakfast.

INTO JAPANESE

私の友人は、私の兄の犬のいとこの妹の隣人を殺した、彼は朝食に食べた。

BACK INTO ENGLISH

A friend of mine, who killed my brother's dog's cousin's sister's neighbor, he ate breakfast.

INTO JAPANESE

私の兄の犬のいとこの妹の隣人を殺した私の友人、彼は朝食を食べた。

BACK INTO ENGLISH

I killed my brother's dog's cousin's sister's neighbor's friend, he ate breakfast.

INTO JAPANESE

私は私の兄の犬のいとこの妹の隣人の友人を殺した、彼は朝食を食べた。

BACK INTO ENGLISH

I killed my brother's dog's cousin's sister's neighbor's friend, he ate breakfast.