Aibo Season 25 to Bring Back Mitsuhiro Oikawa as Ukyo Sugishita's Sixth Partner

A second handoff between familiar partners

TV Asahi announced on October 13 that Mitsuhiro Oikawa's Takeshi Kanbe will replace Yasufumi Terawaki's Kaoru Kameyama as the investigative partner of Ukyo Sugishita, played by Yutaka Mizutani, during Aibo season25. The season begins October 21 at 9 p.m., but the episode in which the change will happen has not been announced.

The decision brings Kanbe back to the central partnership 14 years after his departure from that position in 2012. He originally served as Sugishita's second partner and will now become the sixth. Kameyama, the original partner who returned in 2022 as the fifth, will leave the Special Assignments Unit again for reasons that remain undisclosed.

This is the fifth change of partner in the series, and it repeats a familiar sequence: Kanbe first followed Kameyama after the latter's original departure. This time, however, the transition will take place within a season featuring both partnerships, rather than presenting the returning detective as the established partner from the outset.

The opening episode, PM Crisis, will involve the murder of an aide to Japan's fictional prime minister and an unexpected request from a former student Kameyama taught overseas. That makes Kameyama's past part of the new season's opening mystery, although no connection between that story and his coming departure has been confirmed.

What the sixth partner designation means

Kanbe's new designation does not mean that six different characters have held the position. The numbering counts separate periods in the principal partnership, including the returns of detectives who previously occupied it.

Kameyama was the first partner, Kanbe the second, Toru Kai the third and Wataru Kaburagi the fourth. Kameyama's return made him the fifth; Kanbe's coming return makes him the sixth. The series will therefore have had six partner tenures involving four characters.

The earlier succession provides a useful timeline for the announcement:

• 2000 to December 2008: Terawaki played Kameyama as the original partner, beginning with the television specials and continuing into season7.
• March 2009 to March 2012: Oikawa played Kanbe as the second partner, first appearing in the season7 finale.
• October 2012 to March 2015: Hiroki Narimiya played Toru Kai during seasons11 to 13.
• October 2015 to March 2022: Takashi Sorimachi played Wataru Kaburagi during seasons14 to 20.
• October 2022 onward: Terawaki returned as Kameyama in season21.
• During season25: Oikawa will return to the principal partnership as Kanbe.

The change is described as the first in about five years. The dated history places Kameyama's return in October 2022, four years before the October 2026 season launch; Terawaki also describes his renewed tenure as four full years. Because the coming transition has no announced date, its exact interval from the previous change cannot yet be calculated.

Why Kameyama's departure carries weight

Kameyama's partnership with Sugishita stretches back to Aibo's beginning in 2000. Where Sugishita is calm and analytical, Kameyama is passionate and goodhearted. Their different approaches initially brought conflict, but successive investigations made each indispensable to the other.

His first departure came midway through season7 in 2008. Following the wishes of an old friend, Kameyama went to Salwin, a fictional South Asian country troubled by corruption, to teach children about justice. His exit gave the character a purpose outside policing rather than simply ending his relationship with Sugishita.

When he returned to Japan in season21 in 2022, Kameyama initially rejoined the Special Assignments Unit as a contract employee. He was later formally rehired as a police officer. Season25 takes his partnership with Sugishita into its 12th season across both periods.

Terawaki, who plays Kameyama, said his return still felt recent because he had continued approaching the role with freshness. In comments accompanying the announcement, he promised to keep giving the performance his full commitment until the departure. In English translation, he said:

Until that day comes, I intend to perform with complete sincerity, putting my soul into it!

He also invited viewers to watch how Kameyama leaves the unit. His comments confirm a coming departure, but do not establish whether it will be permanent or whether the character might appear again afterward.

Kanbe returns with a different history

Kanbe entered the series in the season7 finale in 2009 and served as the main partner through season10, which concluded in 2012. Unlike Kameyama, he arrived from the National Police Agency as an elite official with a concealed assignment: to monitor Sugishita and assess whether the Special Assignments Unit was necessary to the organization.

Cool, quick thinking and competitive, Kanbe initially represented the interests of police management. Working alongside Sugishita changed his priorities. He began acting according to his own sense of justice rather than simply following the organization's reasoning.

In the season8 finale, he rejected an opportunity to return to the National Police Agency and chose to stay with the unit. The season10 finale eventually forced his transfer back. He nevertheless remained in contact with Sugishita and has occasionally helped solve cases since then.

That distinction matters when describing the coming return. The 14 years refer to the time since Kanbe stopped being the principal partner, not an uninterrupted absence from Aibo. His renewed position will build on a relationship the series has continued to acknowledge.

Kanbe currently holds a position attached to the secretariat of the National Police Agency commissioner general. Why he will leave that assignment and return to the Special Assignments Unit has not been disclosed.

The actors describe surprise and continuity

Oikawa, who plays Kanbe, said he was surprised when approached about the return. His statement also reflected the unanswered story details, including when the transition would happen and what would bring Kanbe back to the unit.

He described the succession as receiving the baton from Kameyama for a second time. In English translation, Oikawa said:

I want to firmly receive the 'second baton' from my senior Kameyama! And Inspector Sugishita, please go easy on me.

His description of Kanbe combines a cool manner with warmth, professional ability and a tendency to sulk or complain. The statement presents a recognizable returning personality rather than announcing a reinvention of the detective.

Mizutani, who plays Sugishita and remains the lead through the change, framed the decision as something made possible by the show's long history. In English translation, he said:

From Kameyama to Kanbe. This is something that can be done precisely because Aibo has built such a long history.

The two returning partners give that claim a concrete basis. Both have established relationships with Sugishita, and both have already had departures written into the drama. Season25 will revisit those relationships while changing who works beside him.

PM Crisis connects national politics with Kameyama's past

The premiere brings Takamichi Tsutsui and Ryo Kimura into a mystery centered on the sitting prime minister. Tsutsui plays Prime Minister Hikoma Mizoguchi, whose close ally, an aide to the premier, is stabbed to death.

The Special Assignments Unit investigates and visits the prime minister's office to question Mizoguchi. During the inquiry, information emerges that a weekly magazine's editorial office has received an anonymous telephone call from someone offering to reveal a secret about the prime minister that would astonish the public.

At the same time, Kameyama receives a message from a former student from his years in Salwin. She says she found his contact details through advice from laboratory assistant Daijiro Mitsuya, played by Kimura, and makes an unexpected request of the unit.

The episode brings together the killing of a political insider and aspects of Kameyama's past that even Sugishita does not know. His time abroad is therefore an active part of the opening case, rather than merely the explanation for his earlier absence.

The announced plot does not identify this case as the cause of the partner change. Treating the student's request, the political murder or Kameyama's undisclosed history as an explanation for his exit would go beyond what has been revealed.

Six reruns revisit the partnership before the launch

TV Asahi will begin an Ukyo & Kaoru Memorial Selection on October 14, revisiting six episodes associated with Sugishita and Kameyama. The broadcasts are scheduled for the Kanto region in the second part of the weekday Gogo Wide programming block, from 3:50 p.m. to 4:48 p.m.

The selection includes Kameyama's original departure and his return 14 years later, alongside two investigations from the earlier partnership. The announced schedule is:

• October 14: Season7, episode8, Level 4, first part.
• October 15: Season7, episode9, Level 4, second part, Kaoru's Final Case.
• October 16: Season3, episode11, An Ordinary Murder.
• October 19: Season5, episode15, Traitor.
• October 20: Season21, episode1, Persona Non Grata, Murder Invitation.
• October 21: Season21, episode2, Persona Non Grata, A Double Conspiracy.

The schedule places the conclusion of Kameyama's return story on the afternoon of the new season's premiere. It gives viewers a chance to revisit both ends of his long absence before watching the season in which he will leave again. The rerun announcement is local to Kanto, unlike the new season's broadcast across TV Asahi's network.

Broadcast details and milestones need distinction

Aibo season25 is scheduled to begin October 21 across TV Asahi's network of 24 stations. Regular episodes will air on Wednesdays from 9 p.m. to 9:54 p.m. The detailed premiere listing gives an extended slot from 9 p.m. to 10:09 p.m., a duration of 69 minutes.

Reports differ on that opening episode's length: one description calls it a two hour premiere, while the explicit start and finish times indicate 69 minutes. The detailed listing therefore does not support describing PM Crisis as a two hour broadcast.

The anniversary wording also varies. Aibo began as a television special in 2000 and became a regular series in 2002. Its 25th anniversary fell in 2025; season25 is the 25th numbered season, arriving in 2026, when the franchise is 26 years old. Terawaki's comments refer to those 26 years, including the original specials.

With more than 460 episodes broadcast, the new season is reported to take Aibo beyond the 24 seasons of Kasouken no Onna, setting a TV Asahi record for the number of seasons in a continuing drama series. Those figures describe separate measures: the show's age, its season count and its episode total.

The production remains a TV Asahi and Toei collaboration. Announced creative personnel include writer Yasuhiro Koshimizu, director Hajime Hashimoto and composer Yoshihiro Ike. The next fixed date is the October 21 premiere. No episode number, departure explanation or separate date for Kanbe's return has been announced.

Key Points

• Takeshi Kanbe, played by Mitsuhiro Oikawa, will replace Kaoru Kameyama during Aibo season25.
• Kanbe becomes the sixth partner tenure, involving four different characters across the series.
• The season begins October 21 at 9 p.m.; the detailed premiere listing ends at 10:09 p.m.
• PM Crisis combines the murder of a prime minister's aide with a request from Kameyama's former student.
• Six Kanto reruns begin October 14 and include Kameyama's original departure and 2022 return.
• The timing of the handoff and the reasons for both detectives' moves remain undisclosed.