そいつは君の妹と関係を持っているんだぞ!の英語

That guy is having an affair with your sister!

How pretty your sister is!

I think it is unfortunate that I'm cousins with you.

I'm dating my sister's boyfriend's sister.

I'm afraid you mixed her up with her sister.

What has become of your sister?

Do you feel like you'll marry my younger sister?

Your sister is just like you.

He has relations with the girl―a connection with the girl―an intrigue with the girl―a liaison with the girl.

I talked with your younger sister.

Is she you sister?

Is she your sister?

Is that your sister?

Is that person your younger sister?

How are things going with your youngest sister?

Would you intercede with him for my sister?

What grade is your sister in?

Your sister is the most diligent of all my friends.

I confused her with her sister because they are so alike.

I appreciate you getting along with my younger sister.

Surely, your younger sister is skilled at mahjong.

Just between you and me, do you love my sister?

Just between the two of us; are you in love with my sister?

He has a crush on your sister.

Who does your sister take after?

Who is the student talking with your younger sister?

Say hello to your sister for me.

His sister and I will be good friends.

What grade is your sister in?

I'd like to see your sister.