Choen of Buzen is represented by two works designated , neither bearing his signature: an unsigned attributed to him and a dated Kenpo 1 (1213) that has long been handed down as his. The published sources record that 「長円は豊前に住した刀工で、時代を永延頃と伝えている」 (Choen was a swordsmith who lived in Buzen, and tradition places him around the Eien era, 987 to 989), and they note that 「長円有銘の作は頗る少く」 (signed works by Choen are exceedingly few).
The is and unsigned, a blade of fairly high curvature, slender, with a , and it comes with a black lacquered mounting bearing a wisteria crest. Its is a tightly forged mixed with , with fine and , running to toward the edge, and the whole has a slightly whitish cast. The is a with a tight and , and the is straight with a . The sources draw the regional point from the temper: 「刃文は細直刃で、うるみどころがあって九州物の特色をよく示している」 (the temper is a fine with places of , well expressing the character of Kyushu work), and they conclude 「古風で地刃共に優れた刀である」 (an archaic sword, excellent in both and temper).
The is a blade of well-judged width with uchi-zori. It is forged in with a tendency to and a slightly sticky, texture, with fine ; the temper is in tone, becoming mixed with in the lower half and especially on the , with throughout and , and the is straight to a with slight . The tang carries a crest, whether a chrysanthemum or the sun is unclear, then Kenpo 1 on the and the cyclical year kiyu on the , with no maker's name. The sources reason that 「長円の初代は豊前で永延の頃と伝えられているから、建保の年紀を見るこの短刀はその後代の作ということになる」 (since the first Choen is said to have worked in Buzen around Eien, a dated Kenpo would be the work of a later generation), and they add that even if it is not by Choen at all, the Kenpo date is valuable and the workmanship good.
The record under this name is therefore one of tradition: an archaic Kyushu with that the sources accept as Choen's manner, and a dated Kenpo that they place, with explicit reserve, in a later generation of the line.