Once the poet Chōmu (蝶夢)*1 compiled in the first year of Jōkyō (貞享, 1684) a provenance for the Tsurumaru-Kuninaga (鶴丸国永) which says that it was once worn by Taira no Koremochi´s (平維茂) grandson Jō Tarō Sadashige (城太郎貞茂). In Eishō six (永承, 1051) Koremochi´s son Shigemochi (繁茂) assumed the office of Dewa Jōnosuke (出羽城介), i.e. he became the governor of Dewa and Akita province.
From the Kamakura period onwards, this office was renamed Akita Jōnosuke (秋田城介) and because of the name Jōnosuke, Shigemochi´s successors, like Tarō Sadashige, took the family name Jō (城). On the other hand, the sword chronicle Go Tōken Ki (御刀剣記) of the Date family writes that around Hōgen (保元, 1156-1159) the sword was originally owned by a certain Murakami Tarō Nagamori (村上太郎永守) from which it came into the possession of Seino Saburō Nyūdō (清野三郎入道). The Seino were a Shinano-based branch of the Murakami family. With the next owner Jō Mutsu no Tarō Chikanboku (城陸奥ノ太郎近延) – a successor of the Heian-period Jō family – the sword was, according to tradition, lost in the turmoils of the Mongol invasion of 1281. The chronicle says that he killed many Mongols with it before he died in one of the countless skirmishes. Later, the regent Hōjō Sadatoki (北条貞時, 1271-1311) ordered a search for the sword. It was actually found and given to the treasury of the Hōjō but the provenance of the Date family has to be taken with a grain of salt because the Ki´ami Hon Mei Zukushi (喜阿弥本銘尽) from the Nanbokuchō period says that there were actually two swords by Kuninaga. One which was in the possession of Seino Saburō Nyūdō and another one, quote “a tachi by the same smith was worn by Jō no Tarō (城ノ太郎).”
So the logic explanation would be that the Tsurumaru-Kuninaga was in the Jō family until the Mongol Invasion and that the Murakami or Seino family owned a different blade by the same smith. However, after the fall of the Hōjō in the last years of the Kamakura period, the trace of the sword is lost again. It pops up again on surface more than 200 years later in the possession of Oda Nobunaga who presented it to one of his retainers called Mimaki Kanbei (三牧勘兵衛). Kanbei had no son so he gave the sword to his daughter as a dowry when she married into the Matsuda family (松田). This daughter bequeathed it to her lastborn, one and only son, Sokai (素懐) who was a priest. Sokai was well educated and took on the task to find out more about the treasure sword of his family.
So he took it to the Hon´ami family who, to his surprise, asked him: “Your blade reminds us very much of the meibutsu Tsurumaru of the Hōjō family. Do you have any accompanying documents about the provenance of your piece?” Immediately Sokai visited his family and searched the entire residence for any useful records. And indeed, he discovered a letter by Akechi Mitsuhide in an old chest which mentioned that the sword in question was in the possession of Nobunaga and that it had been handed down through the generations within the Hōjō family. This was the proof that the blade was the Tsurumaru-Kuninaga and so Sokai visited the aforementioned Chōmu and ordered a fine and clean calligraphic copy of the provenance of the sword.
The “rediscovery” of the famous sword made the rounds and so it came that the Date family bought it through the agency of the Hon´ami. The price was probably around 200 gold pieces because this was the value which was issued on the contemporary origami from the 16th year of Genroku (元禄, 1703). The sword became one of the most precious treasure swords of the Date and was later presented to emperor Meiji when he visited Sendai in 1876.
Let us now turn to the nickname of the piece. The Kyōhō Meibutsu Chō mentions briefly: “Details on the name Tsurumaru are unknown.” In the Date sword chronicle Go TōkenKi we read: “Habaki ni rindō o sukasu. Yotte, ´Rindō´ to nazuke. Mata Tsurumaru to gō-su.” (鎺ニ輪当を隠す。依而、利不動と名付。又鶴丸と号す), which translates as „The habaki*2 shows sukashi openings in the form of a rindō (竜胆, Japanese gentian, Gentiana scabra). Therefore [the blade] is called Rindō (利不動). But there is also the nickname Tsurumaru (鶴丸).” It is safe to assume that the Japanese gentian was interpreted in its form as a family crest (see picture below). Interesting is that two different writings (輪当・利不動) were used in this entry for rindō (竜胆).
The Ki´ami Hon Mei Zukushi introduces another version of the name rindō, as well as another nickname for the sword. The entry in question reads: “Rindō to nazuku, saya ni sukasu yuhe nari. Mata wa ´misasagi´ to mo ifu, hori-itasu yuhe nari.” (臨刀トナヅケ、 サヤニスカスユヘナリ。又ハミササギトモ云、ホリイタスユヘナリ), which translates as “Called rindō (臨刀) because of the sukashi openings on [the fittings of] the saya. [The blade] was also called Misasagi because it was excavated from one.”
Misasagi (陵) is an imperial mausoleum or an emperor´s grave. The common interpretation of the term hori-itasu is horidasu (堀り出す) which means “to excavate.” The above mentioned translation is based on this context. So it is assumed that the sword was a burial gift for Hōjō Sadatoki or Jō Mutsu no Tarō Chikanboku. But if this was the case, it must not have been excavated too long after the funeral otherwise the Tsurumaru-Kuninaga could not be one of the best condition blades extant from the Heian period.*3 Some interpret the katakana term hori-itasu with the characters (彫り致す) which could be translated as “carved.” But this interpretation does not come up with any sound context with the term “mausoleum” because the last sentence would then translate as: “[The blade] was also called Misasagi because it has such carvings.”
The Muromachi-era sword script Takeya Kizō Nyūdō Mekiki Sho (武谷喜三入道目利書) speculates on the name Tsurumaru that during the Hōgen Rebellion (Hōgen no ran, 保元の乱), i.e. around 1156, the aforementioned Murakami Tarō had the sword mounted in a koshirae with family crests in the shape of a crane in the round (Jap. tsurumaru, see picture above). This crest was a popular and auspicious decorative element for fittings and, first and foremost, for tachi saya of the early and mid Kamakura period. This can be backed-up by extant pieces. For example, on a sword which was offered by Fujiwara no Yoritsune (藤原頼経, 1218-1256) in the first year of Ninji (仁治, 1240) to the Itsukushima-jinja (厳島神社), or on a tachi that belonged to Minamoto no Yoshitsune (源義経, 1159-1189) and which is preserved in the Kurama-dera (鞍馬寺).
Most experts today follow the approach of the Takeya Kizō Nyūdō Mekiki Sho, this means that the name of the sword goes back to its original scabbard ornamentation and that somewhat later another mounting was made whose fittings featured the rindō crest. The swordsmith Kuninaga by the way dates to around the Tengi (天喜, 1053-1058) era. He was according to tradition the younger brother or son of Gojō Kanenaga (五条兼永) and he lived in the Bōmon district (坊門) in the vicinity of Kyōto’s Gojō axis (五条).
gyobutsu, tachi, mei “Kuninaga” (国永), nagasa 78.8 cm, sori 2.7 cm
*1 Because of this date it can´t be the famous Chōmu (1732-1796) of the same name.
*2 This was the original habaki, i.e. the former piece before the Date family had ordered a new tachi-koshirae.
*3 Of course, the Mikazuki-Munechika (三日月宗近) is older, but from the point of view of perfection of forging technique and condition, the Tsurumaru-Kuninaga is clearly superior to the Mikazuki-Munechika.