ため口
I speak casually.
私は話します
I speak casually with my friend.
私は友達にため口で話します
I speak casually with my friend in the club room.
私は部室で友達にため口で話します
I speak casually with my friend in the club room now that we have got close.
私は親しくなった後に部室で友達にため口で話します
I speak casually with my classmate in the club room now that we have got close.
私は同期と親しくなった後に部室で友達にため口で話します