XD!! Okay, our social lives are clearly way too busy. But Sunday morning is cool, as long as you get here before 12 because we're meeting up for the dessert buffet then. :D

As for the train lines, are you arriving via Omiya station? :O If it's from Tokyo station, you can catch the JR Keihin-Tohoku line to Minami-Urawa, then switch to the JR Musashino line to Niiza.