At the end of season 2, note that Yuuri return trip from the earth to the kingdom of Satan using the power of Shin'ou. Since Shin'ou has died at the hands Yuuri, he and his friend Ken Murata could no longer go to the Shin Makoku. However, Murata seems to have learned that, if you can beat Shin'ou Yuuri, Yuuri had the means to their own strength to get back to Shin Makoku. And Murata true.