YOU SAID:

i need to brush my teeth because i have a furry convention later this day

INTO JAPANESE

この後毛皮の大会があるので歯を磨かなければなりません

BACK INTO ENGLISH

I have to brush my teeth because I have a fur competition after this.

INTO JAPANESE

この後毛皮のコンテストがあるので歯を磨かなければなりません。

BACK INTO ENGLISH

There's a fur contest after this so I have to brush my teeth.

INTO JAPANESE

この後毛皮コンテストがあるので歯を磨かなければなりません。

BACK INTO ENGLISH

There's a fur contest after this so I have to brush my teeth.