 If you liked
Maoyuu Maou Yuusha
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 ...then you might like
Tsuyokute New Saga
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Tsuyokute not as much ecchi scenes, but very much about a hero who sets out to defeat/kill the demon lord, but ends up with some unexpected results in the end.
Very similar in the fact that the Hero sets out to make the world a better place, going on adventures planning for the improvement of the human race.
Medieval style ya digg?