The NHK taiga drama for 2027 — the year-long historical serial — is “Gyakuzoku no Bakushin” (The Traitor Retainer), with Oguri Kōzukenosuke Tadamasa as its central figure. This page keeps two things apart: what has been announced officially, and the history the drama will be drawing on. The first half is the announcements, the second half the facts about Oguri as the sources give them.
What has been announced
Title The taiga drama “Gyakuzoku no Bakushin”. It is the sixty-sixth in the series.
Broadcast From January 2027. Oguri was born on the twelfth day of the second month of 1827, so it falls in the two-hundredth year from his birth.
Central figure Oguri Tadamasa, played by Matsuzaka Tōri.
Screenplay Adachi Naoko, writing her first taiga drama.
Executive producer Katsuta Natsuko. Director, Nishimura Takegorō.
Announcement 3 March 2025, at the NHK Broadcasting Center in Shibuya, Tokyo.
Cast Ōsawa Takao as Katsu Kaishū. Further cast members have been announced in batches since 2025 (the people Oguri meets at Edo Castle on 23 June 2026, those connected with the Oguri and Katsu households on 28 August 2026).
According to NHK, the drama will show the end of the shogunate from the viewpoint of a shogunal official whom the new Meiji government treated as a traitor and whom history then buried, and will work in the diplomatic and intelligence struggles of the period. At the announcement, Matsuzaka Tōri said that viewers would be able to see the period from the side of the shogunate's own men.
On the other hand, the number of episodes, the theme music, the narrator and the shooting and location plans had not been made public when this page was checked. Nor has it been announced how far, or in what way, the events and people listed below will be shown. From here on, read this as history.
Sources: the NHK announcement of the taiga drama “Gyakuzoku no Bakushin” (3 March 2025); the City of Yokosuka, “On the decision for the 2027 NHK taiga drama Gyakuzoku no Bakushin” (5 March 2025); NHK cast announcements (23 June and 28 August 2026). Checked 6 October 2026.
What “traitor” was
The word in the title was not one Oguri used of himself, nor a name given him as the outcome of any trial. Taken in order, it went like this.
On the twenty-second day of the fourth month of 1868, the headquarters of the Tōsandō expeditionary force sent the three domains of Takasaki, Annaka and Obata a circular ordering Oguri's arrest. It read as follows.
Reports have come in from several quarters that Oguri Kōzukenosuke has of late raised a fortified encampment in his fief at the village of Gonda in Kōzuke, and has built a gun battery besides, and is engaged in no light design; such reports could not be left unheeded, and on close enquiry the treasonous plot is manifest. Toward the Court above, this is insolence of the worst kind; below, it runs counter to his master Yoshinobu's submission. The domains are therefore ordered to apprehend him.
“Gyakubō hanzen” — the treasonous plot is manifest. Those four characters became the premise of everything that followed. The circular was addressed to Matsudaira Ukyō-no-suke, lord of Takasaki, Itakura Kazue-no-kami, lord of Annaka, and Matsudaira Tetsumaru, lord of Obata, and was issued by the secretariat of the Tōsandō headquarters. The commander of the Tōsandō force was Iwakura Tomosada, a son of Iwakura Tomomi, and under him were the staff officers Itagaki Taisuke and Ijichi Masaharu, together with Kagawa Keizō, Nanbu Seitarō, Nishimura Sutezō and Ōne Ryūtarō. No record states who drafted the text.
Abe Dōzan's Kaigun no Senkusha Oguri Kōzukenosuke Seiden (a true life of Oguri Kōzukenosuke, pioneer of the navy) presses this wording hard. It says “on close enquiry the treasonous plot is manifest”, and yet there is no evidence of any enquiry: “not a hair's breadth of anything manifest. It is no more than a form of words leading to an arrest.” And in the line added at the end — “this is to be attended to with urgency” — he sees a headquarters driven by rumour.
The premise of the circular collapsed on the spot. On the first day of the intercalary fourth month, representatives of the three domains came to Tōzenji in the village of Gonda and went through the terms of the order one by one. There was no encampment, and no battery. What there was: a house half-built on Kannonyama, and French-made weapons brought from the Edo residence. Telling them to make it the ground of their report, Oguri handed the three domains, there and then, the one cannon and twenty-one rifles he had with him. The three domains withdrew, stating that it was plain there was not a single trace of a plot. Oguri, having nothing to hide, sent his adopted heir Matakichi Tadamichi to present himself at the headquarters' camp at Takasaki.
What Oguri said to the representatives that day is recorded in Ōtsubo Sadakata and Hozumi Odoroki's Oguri Kōzukenosuke.
Kannonyama here has long been woodland held by the house of Oguri, and although I have levelled the outer field and begun building a house, it is no more than will keep off rain and dew. That the work is nothing like a stronghold will be plain at a glance, if you will let me show you round at once. And would a man setting up a treasonous plot or a conspiracy open fields and paddy about his house and call it a plan for later years? Examine it fully, and understand that I am not a man harbouring any other intent.
He added that if they would show him so much as one ground that could serve as evidence, he would answer it without fail. What he asked for was a chance to answer. That it was never given is the heart of the affair.
Matakichi and three others, however, were seized at once and thrown into the jail at Takasaki. The man who called this handling too soft was Hara Yasutarō, the inspecting officer under Iwakura Tomosada. Early on the sixth day of the intercalary fourth month, Oguri and three retainers were taken out to the riverbed at Mizunuma on the Karasu River and beheaded, without being examined at all. Oguri was forty-two by Japanese count. Abe Dōzan asks why, “in defiance of such an official order, the officers in the field beheaded him complacently without granting him a single hearing”, and points out that the arrest order had not commanded a beheading in the first place: “however many cannon there may be, and even had a position been built, nothing instructs them to behead him.”
And the name “traitor” was fixed on him broadly after he was killed. Abe Dōzan notes that at Fumon'in, the Oguri family temple at Ōmiya in Saitama, more than twenty of the family's graves were left toppled; that, having beheaded an innocent man, the imperial troops exposed his head unlawfully and “worked at the propaganda of the traitor”; and that “the villagers believed this false propaganda”. Even in the Shōwa era, he writes, he was taken aback to find people in Oguri's former fief still being told that he had been a traitor.
Half a century passed before the name came off. On the twenty-seventh of September 1915, at the ceremony for fifty years since the founding of the Yokosuka naval yard, the head of the arsenal, Vice-Admiral Kuroi Teijirō, published an official document honouring Oguri's achievements: of the rebellion so long reported there was no trace whatever, to call him an enemy of the Court was unthinkable, he was on the contrary a great servant of the state. “Traitor”, then, was not a finding of history but a name written for the purpose of an arrest and spread after a killing. The title of the drama points to that name.
The commemoration reached the temples as well. In the grounds of Fumon'in at Ōmiya, the temple of the Oguri family, a stone for the summoning of Oguri Kōzukenosuke's spirit was raised, its title inscribed by Tokugawa Iesato and the text on its reverse written by Ninagawa Arata. It begins, “To open the country is to raise the country. That the shogunate carried the opening through was an act of love for the country,” and of Oguri it says that as the first envoy sent abroad he discharged his country's charge in full, and that state policy in finance, trade, industry, diplomacy and defence was begun by him: “he was truly a man of patriotism and loyalty.” It records him too as the foremost man of foresight of his day, who held the broad design of doing away with the feudal domains and setting up prefectures.
Sources: Abe Dōzan, Kaigun no Senkusha Oguri Kōzukenosuke Seiden (a true life of Oguri Kōzukenosuke, pioneer of the navy), Kaigun Yūshūkai, 1941; Oguri Nikki (the Oguri diaries), Gunma Prefecture Historical Materials vol. 7; Ōtsubo Sadakata and Hozumi Odoroki, Oguri Kōzukenosuke, Oguri Kōzukenosuke o Shinobu Kai, 1975; Kurabuchi Mura-shi (the Kurabuchi village history)
→ The arrest circular of the twenty-second day of the fourth month, and the three domains' troops ／ The sixth day of the intercalary fourth month: the end at the riverbed at Mizunuma ／ 1915: the rehabilitation at Yokosuka
The events the drama will deal with
Oguri stood on the public stage for about eight years, from his return in 1860 to 1868. In that time he held, some of them concurrently, the posts of commissioner of finance, Edo city commissioner, commissioner of infantry, commissioner of the army and commissioner of the navy, and the attendants at the castle joked that Oguri had changed office yet again. The main turning points follow.
Eighteenth day of the first month, 1860 The embassy to the United States sails from Shinagawa Shinmi Buzen-no-kami Masaoki as chief envoy, Muragaki Awaji-no-kami Norimasa as vice-envoy, Oguri Bungo-no-kami Tadamasa as inspector, and seventy-seven men in all went aboard the Powhatan. They reached Washington on the twenty-fifth day of the third month and exchanged the ratifications of the treaty on the third day of the fourth month. The United States Navy's Washington Navy Yard, which they saw there, led in time to Yokosuka.
→ Sailing Washington The negotiation at the Mint Tommy1861 The Tsushima incident The Russian warship Posadnik settled itself at Imozaki on Tsushima, put up barracks and began surveying. Oguri, commissioner of foreign affairs, left Shinagawa on the sixth day of the fourth month and negotiated three times aboard the ship in the fifth month. Against a party that would not move for anything but force, he recommended bringing Tsushima under direct shogunal rule and building up naval strength; this was not accepted, and on the twenty-sixth day of the seventh month he resigned as commissioner of foreign affairs. He was thirty-four.
→ The Tsushima incidentTwelfth month, 1864 A word in the street at Yokohama He stopped Kurimoto Sebei (later Joun) on a street corner and put to him what might be done with the machinery presented by the Saga domain. Kurimoto wrote in his notes that he was “hearing the word dock for the first time”; Oguri, for his part, had the memory of the navy yard he had walked through four years before.
→ Meeting Kurimoto JounTwenty-seventh day of the ninth month, 1865 The ground is broken for the Yokosuka ironworks The chief engineer was Verny of the French navy. “Ironworks” meant a general works handling iron; it became the Yokosuka shipyard. The dry dock built there is still in service today.
→ The Yokosuka ironworks The dock The French school at YokohamaFourth month, 1867 The proposal for the Hyōgo Shōsha “A memorandum on the opening of the port of Hyōgo, on the founding of a trading company, and on the prospect for the funds required.” Oguri uses the word “konpenī” — company — in it. On the fifth day of the sixth month, twenty wealthy merchants of Osaka were gathered at an inn in Kyoto, and the Hyōgo Shōsha was founded with Kōnoikeya, Kajimaya and Hiranoya among its officers.
→ The Hyōgo Shōsha Minomura RizaemonThirteenth day of the first month, 1868 The great council at Edo Castle After the news of the defeat at Toba and Fushimi, Oguri went up to the castle past the fifth hour of the morning and left at the eighth hour of the night — sixteen hours of argument. He pressed Yoshinobu to fight on, and was not heeded.
→ Sixteen hours of council The return of power to the emperorTwenty-eighth day of the first month, the same year The petition to settle at the village of Gonda He asked to give up his fief, settle in the village of Gonda in Gunma district, Kōzuke province, and raise a peasant militia as his small service to the state. He left Edo on the twenty-eighth day of the second month and reached Tōzenji at Gonda on the evening of the first day of the third month.
→ The petition to settle, and the journey to GondaThird and fourth months, the same year The building on Kannonyama, and the Odaka water channel Work on the house began on the sixth day of the third month, and the ridgepole was raised on the fifty-second day, the twenty-eighth of the fourth month. The channel he laid out by French survey for the neighbouring hamlet of Odaka was finished after his death and is still in use. On the third day of the third month a mob calling itself the Oguri expedition came down on Sannokura, and Matakichi and his men drove it off.
→ Kannonyama The fight at SannokuraSixth day of the intercalary fourth month, the same year The riverbed at Mizunuma On the seventh, Matakichi Tadamichi too was beheaded inside Takasaki castle. He was twenty-one by Japanese count.
→ The end at the riverbed at Mizunuma Matakichi Tadamichi
The people who had dealings with Oguri in the record
Those named here are people who actually had dealings with Oguri in the sources.
Family His mother was Kuniko, written 邦子; some sources write it 国子, with the characters of his daughter's name. His wife Michiko was a daughter of Tatebe Takumi-no-kami Masaatsu, lord of the ten-thousand-koku domain of Hayashida in Harima, born in 1839 and twelve years younger than Oguri. His adopted heir was Matakichi Tadamichi, his adopted daughter Masako. After the disaster the household went in two parties, one around the pregnant Michiko and one with the mother, Kuniko, and Masako; the second escaped Gonda disguised as pilgrims bound for Zenkōji, and the two met again at Aizu. The girl born in the castle town of Aizu on the fourteenth day of the sixth month of 1868 was Kuniko. The name appears to have been taken from her grandmother's, and Ōtsubo Motoji's Oguri Kōzukenosuke Tadamasa Kakei oyobi Ryaku-nenpu (the genealogy and short chronology of Oguri Kōzukenosuke Tadamasa) records her as “the only blood of the house of Oguri”.
→ The flight to Aizu Kuniko His marriage to Michiko
Colleagues Kurimoto Joun, a son of one of the shogun's own physicians, was an unusual figure who returned to government service by way of Hakodate; he carried the Yokosuka plan forward with Oguri. Verny was a French naval engineer trained at the École Polytechnique, chief engineer of the ironworks. Minomura Rizaemon rose from a servant living in the Oguri residence to be chief manager of the house of Mitsui, and called on the Oguri household four times just before the move to Gonda, on the fourth, fourteenth, twentieth and twenty-fourth days of the second month. Mukasa Yūzaemon was the chief steward, in service since the time of Oguri's father Tadataka. The embassy to the United States also included Kimura Yoshitake, commander of the Kanrin Maru, and his attendant Fukuzawa Yukichi.
→ Kurimoto Joun Verny The Mukasa family Kimura Yoshitake Fukuzawa Yukichi
Katsu Kaishū Born in 1823, four years older than Oguri. Both came out of the Jikishinkage school and the fencing hall of Onogai Seiichirō. On the policies of the last years of the shogunate they never agreed, and Abe Dōzan holds that one cause of the climate in which the name of traitor “was forced on him” lay in what Katsu said.
→ Katsu Kaishū
Hara Yasutarō Inspecting officer of the vanguard headquarters of the Tōsandō force. He seized Oguri at the village of Gonda and directed the execution. Born into a poor samurai family at Sasayama in Tanba, a swordsman, he said himself that he was still twenty-two when he set out for Gonda.
→ Hara Yasutarō Ōkuma Shigenobu Those who came to Fumon'in
Visiting the places
The places divide into three: Gunma (his last days and his grave), Yokosuka (the traces of his work) and Tokyo (where he was born and grew up).
At Kurabuchi in Takasaki, Gunma, stands Tōzenji, where Oguri lodged in the village of Gonda and which now holds his grave. The grave and a display of his effects are in the grounds. At the riverbed at Mizunuma, the place of the execution, stands a memorial stone whose text reads, “A great man, Oguri Kōzukenosuke, cut down in this place without crime.” It was unveiled on the fifth of May 1932; the words and the calligraphy are by Ninagawa Arata, the scholar of international law who was a nephew of Oguri's wife Michiko. About a kilometre downstream from Tōzenji, on the terrace above, is the site of the house on Kannonyama, where the foundation stones and the water channel remain.
At Yokosuka, the busts of Oguri and Verny stand side by side in Verny Park, unveiled in September 1922, the work of the sculptor Asakura Fumio. In the Verny Memorial Museum in the same park is a steam hammer used at the ironworks. In Tokyo there are the site of the house at Kanda Surugadai where he was born, and the Oguri family grave at Zōshigaya cemetery.
Opening hours, admission and closing days change, so please check each place's official pages before visiting.
→ The places The grave at Zōshigaya The busts at Yokosuka
Reading before the broadcast
To get a first sense of the man, the quickest way is to begin with Who Oguri Kōzukenosuke was. From there, for the original accounts: Sakamoto Fujiyoshi's Oguri Kōzukenosuke no Shōgai (the life of Oguri Kōzukenosuke), Abe Dōzan's Kaigun no Senkusha Oguri Kōzukenosuke Seiden, Ōtsubo Sadakata and Hozumi Odoroki's Oguri Kōzukenosuke, and the Oguri Nikki. What each of them is, and how to get hold of it, is set out in reading the books and following the sources. As the broadcast comes closer, the list of all articles may be a help too.
→ Who Oguri Kōzukenosuke was Reading the books Following the sources Chronology