The third formal Isshin-ryu kata learned is Naihanchin, taken from Shorin-ryu. The name can be translated as "iron horse" and the distinctive toes-in naihanchi stance (uchi hachiji dachi) provides a stable, but maneuverable, base for the upper body.
Naihanchi was designed to teach lateral, close-in combat against opponents on both sides, such as when fighting with one's back against a wall. Some historians say that the original versions were developed for combat in the rows of rice paddies.