Ditto on the economics. Because if it is really like medieval Japan, then my economist character will have quite a lot of work to do.

Such as inventing double-entry bookkeeping just to make the complex task of accounting more manageable, that way she can spend more time with her lord. (Really, medieval Japanese accounting was very time and manpower consuming. Any improvement would be a major boon to economics overall.)

In fact, theres plenty of time period appropriate economic innovations my char could try in order to win over her love with ink and paper instead of swords.