A great series about a 15 year old boy named Yuri who is transported to another world through a toilet and then finds out that he is the king of "The Great Demon Kingdom" which is one of the more powerful countries there.
Volume 3 starts out with Yuri being held captive by the previous ruler's(Queen Celie) brother. Having been captured in the last episode of volume 2. After that Yuri get word of someone in a nearby country who has been using the name of he demon king and to top it all off they got them selves arrested and are going to be put to death. Yuri being the nice guy that he is decides to go help him. But on the way Yuri ends up alone in a foreign country