In this episode, we approach the secrets hidden in Matsuyama Castle and follow a group of soldiers as they attack the castle, facing a 400-meter-long stone wall in the mountain, a doorless gate, a gate that enables ambushes, and the final defense at the tower keep. CG and drones are used to introduce the defensive features that await them. We also investigate the truth about "ishi-otoshi" or stone dropping chutes and their actual purpose.