“When you infiltrate the enemy line and come to a naturally fortified place, use the appropriate tools to gain entrance successfully. To get into an impregnable castle with a high stone wall, a high fence, a barrier, or a castle not naturally fortified but well constructed, or even one fortified with water such as a river, it is essential for you to prepare yourself with useful tools before you embark on a shinobi mission. In addition, you need to use the appropriate weapons when you invade the enemy's residence. This chapter shows how you create these tools.”