After you win a battle in Muramasa: The Demon Blade, you'll get a list of rewards for things you did during the battle, like "Quick Draw Finish" for killing an enemy with a quick draw attack or "Completed Unscathed" for clearing the fight without taking any damage.
One that I get every now and then, but cannot figure out what it is, is "Fortune Strike". As far as I can tell, I haven't been able to find any consistent method of earning this one. It's not really worth much, but considering I can at least tell how I received the others, this one is just confounding me all the time. What are the requirements for receiving this bonus, exactly?