Yoku Wakaru Gendai Mahou Temporada 1 Episódio 6

Still in the past Koyomi decides joins forces with Yumiko in order to stop Guibarthez rather than returning to her own time straight away. However, when Guibarthez manages to get a hold of Kerykeion the girls may no longer be able to stop him, and even the timely arrival of Misa may not help them.