Talk:Touya Mochizuki/@comment-7861128-20171212072609/@comment-26956659-20171221163954

The author indeed uses certain information as a guide when he create this fictional story but please remember all material that exist is in Japanese not English. Language is closely related to culture which has probability to make certain phrase that is logical to certain language but when literally translated into other language become non-sense because of cultural differences.

Official translation usually adapt with the source material which means they will change their translation into more fitting translation for the overall story structure.

There is other user who also said that the official english translation (by J-Novel) of Touya's title is grand duke. While here we have you presented us with other translation calling Touya's title as king.

So, I think it is as simple as when there is a kingdom, the ruler is called a king. An empire for an emperor, therefore a grand duchy for a grand duke.

further discussion: http://isekai-smartphone.wikia.com/wiki/Thread:1356