>>1889302European monarchs did not claim to be descended from God. To do so would be considered blasphemous. That's not to say they didn't evoke God in their right to rule, but that's a different thing. Even the Roman emperor did not claim a divine heritage. Instead they, along with future European monarchs claimed to have a special divine right.
It wouldn't even make sense for most European monarchs to claim divine heritage, because unlike the Japanese monarch which has descended from the same familial line since it was established, people from various families have occupied European monarchies.