Play through the game until you obtain the six items needed to unlock the gates in the room with six triangles. Once you have that equipment, restart the game in Bloodline One. Before you fight anyone, change your gear so that you are equipped with the worst available equipment (the default gear that was available when you first started the game in the castle area). Now fight the first enemy, a ninja, and you should see that the prompt to block his attacks doesn't display. Let him kill you. Once you die and the option appears, indicate that you wish to restart the game on the previous bloodline. Since there is no previous bloodline available, the game will not recognize that you have already obtained the valuable gear. Play again now and return to the room with the triangles for a fresh set of equipment. Continue from there and fight to obtain the large key, then reset to Bloodline One again. You can repeat the process as often as you like. Each time, you will get more valuable equipment that you can sell for a bunch of gold, as well as another large key.