Complex sentence: Sugimura first noticed Kayoko Kotohiki when he saw her taking a flower arranging (ikebana) class in the same building where he practiced martial arts and afterwards everyday he would stop outside the room she worked in and watch her.
Split into simpler sentences: Sugimura first noticed Kayoko Kotohiki when he saw her taking a flower arranging (ikebana) class in the same building where he practiced martial arts. Afterwards everyday, he would stop outside the room she worked in and watch her.