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| Rina Koyama and M!LK’s Daichi Shiozaki Reportedly in 10-Year Relationship, Shukan Bunshun Claims. |
Japanese magazine Shukan Bunshun has claimed that M!LK member Daichi Shiozaki, 25, has been in a long-running relationship with actress Rina Koyama, 23, with the publication teasing photographs and details from what it describes as a private romance between the singer-actor and the former Sailor Moon musical performer.
The report, published on 16 August 2026, has immediately put Shiozaki's personal life under the spotlight, particularly because the magazine's teaser points to an alleged relationship stretching back around 10 years.
Rather than presenting the story as a brief celebrity rumour, Shukan Bunshun's preview suggests it has photographs and observations that it believes show the two maintaining a remarkably long connection away from the public eye.
According to the report, the story centres on an evening on 30 July, when Shiozaki reportedly returned to his tower apartment relatively early after a busy day.
Shortly afterwards, a woman was said to have entered the same residential complex through another entrance. The magazine then identifies the woman as Rina Koyama, describing the pair as having quietly maintained their relationship while keeping it largely away from public attention.
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| Daichi Shiozaki and Rina Koyama Dating for 10 Years |
The timing is particularly notable because M!LK are currently enjoying one of the biggest periods of their career. The five-member group, which operates under Stardust Promotion, has grown substantially in popularity following the success of their music, with “Ii Jan” becoming a major talking point after its release in February last year. Their momentum has continued into 2026, with “Suki Sugite Metsu!” also attracting strong attention.
Shiozaki has become one of the group's recognisable members, combining music activities with acting and performances that have helped define his public image.
M!LK's rise has also taken the group into increasingly prominent territory, including their first appearance at NHK Kohaku Uta Gassen at the end of last year.
With the group now firmly among Japan's most visible young idol acts, any report concerning a member's private life was always likely to attract considerable attention.
Shukan Bunshun's report describes the relationship as a kind of commuting romance, with Koyama Rina allegedly making frequent visits to Daichi Shiozaki's apartment.
The magazine also points to what it says are smaller clues that had previously appeared through social media and other observations. None of those details, however, should be treated as independently established fact simply because they appear in the report; at this stage, the claims remain those of the publication.
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The story is also likely to generate a particularly complicated response from M!LK's fanbase because idol culture in Japan has historically placed enormous importance on the image and availability of its stars.
Some agencies and idol groups have maintained strict expectations around personal relationships, while others have taken a more relaxed approach. The result is an industry where something that would be considered perfectly ordinary private life for most people can become a surprisingly major discussion when the person involved is a highly visible idol.
Fan reactions to the Daichi Shiozaki and Rina Koyama report are therefore likely to vary considerably. Some supporters may simply shrug and argue that a 25-year-old performer is entitled to have a private life, particularly if the alleged relationship really has lasted for years.
Others may feel disappointed, especially if they have built a strong emotional connection with Shiozaki's public persona. And then there are fans who will probably be less interested in the relationship itself than in the astonishing claim that the two may have known each other for roughly a decade.
That reported timeline is arguably the detail most likely to fuel discussion. If accurate, it would mean the alleged relationship stretches back to a period when both were much younger and before M!LK reached its current level of mainstream visibility.
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It also makes the story considerably different from the usual celebrity rumour cycle, where speculation appears suddenly and disappears just as quickly. Here, the central claim is of a connection that has supposedly continued through years of career development.
For M!LK, the timing could hardly be more interesting. The group are in the middle of a major career upswing, with their recent success bringing them greater visibility across television, music and live performance.
The group's long-held ambition of performing at the Tokyo Dome now looks increasingly realistic, according to comments cited in the report, making Shiozaki's personal life an even bigger talking point than it might have been during M!LK's earlier years.
At the same time, the Shukan Bunshun teaser appears designed to create anticipation ahead of the magazine's fuller report, so readers should distinguish between what has been explicitly claimed and what remains speculation. The photographs and additional details referenced by the publication may provide more context, but they do not automatically settle every question surrounding the pair.
For now, Daichi Shiozaki and Rina Koyama are at the centre of a rapidly developing entertainment story, with the alleged decade-long relationship becoming the detail that has caught the most attention.