Tomoshige is the founder and representative smith of the Fujishima school of Fujishima village in province, the name carried by several generations from the end of through and on into the early-modern era. The earliest dated work found among them is a of Oei 2 (1395), and the published sources treat that date as the chronological anchor for the whole name. The first generation comes down by tradition as a pupil of Kunitoshi of Yamashiro, alternatively of Sanekage of his own province, but the doubts both readings in nearly the words across blade after blade, finding no stylistic tie to Kunitoshi (来国俊とは作風的に結ばれず) and a chronological impossibility with Sanekage, and judging from the make and the finish that the line descends rather from the Yamato tradition, close to the Yamato Shikkake hand. The oldest piece thought to be his, a held at Atsuta Shrine, is read as confirming that distance from the school. No surviving work predates .
The recognition of Tomoshige lives in his . He forges a board-grained that mixes in and runs to , standing somewhat open, the surface gathering and , and the steel carries a distinct blackish cast. The published record names exactly this as the school's chief point, that the stands and tends dark (肌立ちごころで黒みをおびる), the mark of northern-country work. Over that he tempers a into which box-shaped, pointed and angular teeth enter together with and , at times rising into a compound, multi-peaked . The calls the feel of it a make in which temperament and flavor are mixed (備前気質と美濃風が混在した感のある乱れ刃), the rather long, the whole -laden with patches of rough , sweeping the and entering, small scattered here and there. The runs straight or into a and is often swept with . It is the conjunction that identifies him, a Yamato-rooted dark steel under an active temper that borrows from two other traditions.
The repays a closer look, because it is where the school and the man are read. The board grain stands and flows rather than tightening into the fine of a Yamashiro blade, and on the and it sharpens further toward a -leaning , the most plainly Yamato of his . The dark color is not an accident of polish but a property of the steel itself, and the published sources tie it directly to the northern provinces, writing of one dated that the blackish cast of the metal shows the point of northern-country work (地がねの色が黒みを帯びているところに北国物の見どころが示され). Across several blades a faint whitish rises in the , the quiet reflection of northern steel rather than a bright one. The answers the with its own mix: angular and box-shaped teeth are singled out as a point worth naming on the typical work, the enters long, the at times sits in and at times in a deeper , and the activity is constant without ever becoming showy.
Within this single manner the published sources mark the short blades apart. On the the school hand can quiet, the tightening to a , the temper dropping to a narrow or a low with and , the sometimes misty with and , the a that on one piece returns deep into a jizo-like shape. The longer blades carry the box-and-pointed ; the are where the Yamato base of the school shows most simply, even as the dark steel keeps its northern mark. A second, dated register leans further toward Yamato still: the Oei 16 (1409) tempers a base with small teeth and a , and the reads it as a make in which a Yamato temperament can be seen (大和気質が看て取れる) while the dark color of the steel keeps the northern grain plainly shown (北国風の肌合が明示されている). As one of the very few early-dated Tomoshige it is valued as reference material for the school's range. The name is almost always signed, thirteen of fourteen designated blades on an , the four-character Fujishima Tomoshige most common, sometimes a two-character Tomoshige, the single long full signature surviving on one piece alone; the published sources lean on the signature and the date together to read a given blade as the Oei Tomoshige.
What sets Tomoshige apart from the schools his work otherwise recalls is held in his own grounded traits rather than borrowed from theirs. His resembles a make in its and its long , but the box-shaped and pointed teeth, the standing dark and the constant pull it away from a clean ; one is read as showing an air, and one is compared to Naoe and to Sekishu Naotsuna, the and northern lines his own work sits between. The teacher question is settled by elimination toward Yamato, the line bound neither to Kunitoshi in style nor to Sanekage in date. He stands at the head of the Hokurikudo Fujishima manner, in feel to the and smiths of the region, and the name continues for generations on the fixed character of dark standing and box-and-pointed , the Oei smiths the most highly regarded and the work the most often surviving.
Fourteen of his blades stand in the tier, and Fujishiro rates the smith Chu-jo . His finest single work is a great spear, the o-mi- signed Fujishima Tomoshige and carved with a and the deity-name Myoken Daibosatsu, which the judges not merely the best spear of the school and name but one of the representative famous spears of its age (同時代を代表する名槍の一本である). Surviving by him are noted as rare. Provenance gathers around two houses recorded in his own blades: an Oei-period descended in the Inaba house, and a held in the Imperial collection. These are heritage blades held in long-standing hands rather than goods of the market, and the man himself is not among the unattainable names; his designated swords come to auction and to dealers from time to time, a Tomoshige a realistic if uncommon encounter for a patient collector, valued less for rarity at the very top than for the way a single dark-steeled blade carries the whole northern school in its .