Demon Kings All Come from Another World

I traveled through time, but what the hell is going on? Why are the character cards of Shidou Itsuka, Kamito Kazehaya, Arata Kasuga, and Demon Lord Ryusei all in a box in my backpack? There are also many anime characters such as Silica. The strange thing is, why can they be materialized? This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.