I agree on the creativity. I read your opinion on your other post and I don't disagree, since it is a decent series but yes, there was more they could have done with the setting. The filter was just useless, and the princess was indeed lacking. She's not a historical figure like her father, and actually, afaik, we don't know who was the real daughter of Sō Sukekuni, and if he even had one, so there was a lot of room for creativity there, but instead we got some generic tsundere, haha.