Narimune (成宗) is transmitted as a son — or, by some accounts, a younger brother — of Norimune, the founder of the Fukuoka school of Province. His period of activity falls within the early , and extant signed by this smith are exceedingly limited in number. The relationship to Norimune places Narimune at the very headwaters of the tradition, and his works carry a distinctly archaic flavor that the characterizes as possessing a kocho quality.
The forging in Narimune's is a tightly worked with fine adhering, upon which appears distinctly — a hallmark of high-level workmanship. The is characteristically a intermingled with and , rendered in , with and entering well and and appearing here and there. The tends toward , turning back in . The temper is typically narrow in width, and the overall effect is one of restrained, classical elegance consistent with the early Fukuoka idiom. In , his present a slender build with high , pronounced , and — the archetypal early form.
Narimune's surviving works, though few, are prized for their combination of authentic early craftsmanship and the rarity of preserved signatures. The observes that signed by this smith are "limited to only a few examples," lending each extant blade particular documentary significance. While some pieces show a tendency toward , they have "not yet lost their aesthetic appeal," and the — with its conspicuous and fine — confirms workmanship consistent with the highest standards of the early Fukuoka school.