Event Classification with Multi-step Machine Learning Masahiko Saito, Tomoe Kishimoto, Yuya Kaneta, Taichi Itoh, Yoshiaki Umeda, Junichi Tanaka, Yutaro Iiyama, Ryu Sawada and Koji Terashi EPJ Web Conf., 251 (2021) 03036 Published online: 23 August 2021 DOI: 10.1051/epjconf/202125103036