Four Underground Idol Shakeups in October 2026: Payrin’s Disbands, OS☆U and Nanairo ∞ Milky Way Lose Members

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Image source: https://payrins.jp/

In the span of just two days, October 13 to 14, 2026, four organizational changes were announced across the underground idol (chika idol) scene. Payrin’s is ending its activities as a group, OS☆U and Nanairo ∞ Milky Way each announced a member departure, and Shirokumind announced a member’s graduation and exit from her agency.

Here’s the breakdown. Payrin’s will cease activities following the solo concert marking two years of its current lineup on January 23, 2027. At OS☆U, Kayo Tachibana departed effective October 13 over a violation of group rules and is suspending her activities. At Nanairo ∞ Milky Way, Haru Miyai departed on the same date over private contact with fans. At Shirokumind, Nagisa Hoshine graduates following the October 15 live show and is also leaving her agency.

Line the four up and you can see that the nature of the reasons is completely different in each case. Ending activities, a rules violation, private contact, health. They may all get filed under the same phrase – “lineup change” – but the meaning fans should take from each one is separate.

In this article I organize all four based on the official announcements, then wrap up with a side-by-side comparison table. No speculating about reasons.

When will Payrin’s end its activities as a group?

Payrin’s will end its activities as a group following the solo concert marking two years of its current lineup, held at BLAZE GOTANDA on Saturday, January 23, 2027.

After repeated discussions among the members and staff about the group’s shape and its future, we reached the conclusion that, looking ahead, bringing our activities to a close is the best choice.

Source:IDOL REPORT

What stands out is that each member’s own path forward was stated at the same time. Uta Yukimori, Piyori Suzushiro and Hinata Matsumoto have each said plainly on X that they will end their idol careers altogether when the group’s activities end. Miko Tsumugitsuki also issued a comment.

I’d call this simultaneous disclosure an honest way to handle it for the fans. When the news gets split up – the group is ending, but the members’ futures are undecided – fans are left unsettled for months. With more than three months to go before the final solo concert, laying out the outlook up front looks like a decision made to keep the scene from descending into confusion.

Details of the final live show will be announced separately. As of October 2026 there has been no official announcement of how tickets will be sold or what they will cost.

Why did OS☆U’s Kayo Tachibana leave the group?

Kayo Tachibana departed OS☆U effective Tuesday, October 13, 2026. The reason given in the official announcement is that conduct violating the group’s rules was confirmed.

Because conduct violating the group’s rules was confirmed

Source:IDOL REPORT

The official announcement makes no mention of what the violation specifically involved. Tachibana herself is suspending her activities from October 13 as a period to reflect on her own conduct, and anything further will be announced at a later date. As of this writing, there is no post about the departure on Kayo Tachibana’s X account.

The practically substantive part of management’s response was pointing fans who bought tickets specifically to see Tachibana toward a claims form. Groups that open a financial remedy channel at the same moment they announce a departure are, honestly, not that common.

Following this departure, OS☆U will continue as a nine-member group.

What was the reason for Haru Miyai’s departure from Nanairo ∞ Milky Way?

Haru Miyai departed Nanairo ∞ Milky Way effective Tuesday, October 13, 2026. The reason is that private contact with fans was confirmed.

We have confirmed private contact between member Haru Miyai and fans. As a result of discussions with her, she will be departing Nanairo ∞ Milky Way effective today, Tuesday, October 13.

Source:IDOL REPORT

The wording of the announcement is short, but the information it covers is unambiguous. Confirmation of the facts, discussion with the member, and a same-day departure. Writing the sequence of events without obscuring it communicates more to readers than OS☆U’s abstract phrasing of a “rules violation.”

Haru Miyai’s X account has already been deleted. Also, the announcement says nothing about any action against the fans involved in the private contact. This is a point that often becomes a talking point in how rules get enforced on the scene, and whether there will be a follow-up is unclear as of October 2026.

When is Shirokumind’s Nagisa Hoshine graduation show?

Nagisa Hoshine will graduate from Shirokumind and leave her agency following PANDA MUSIC FES mini vol.2, held at Shinjuku DHNoA on Thursday, October 15, 2026.

She had been consulting with us about her health for some time… Putting her health and her future first, we judged that continuing to perform in her current condition would place a heavy burden on her, and we arrived at this decision.

Source:IDOL REPORT

Hoshine herself posted on X that she will absolutely create a place where everyone can meet again, hinting at future activity. Only two days separate the announcement from the graduation show, but when the exit is for health reasons, dragging that decision out would be the heavier thing for her. Management’s priorities aren’t wrong here.

Dollar figures are converted at 153 yen to US$1 and are for reference only.

The lineup features 12 acts: Aisunattsu, FLORERISA, BANKURUWASE!!, Shirokumind, Minority Alert, MeltiaDoll, Amairo-Flip, Lil Amour, Seishun no Frontier, KimiTrial, NEOTOKYO-TRIBE and Precious♡Party.

What do these four lineup changes reveal when placed side by side?

Set the four side by side and you can see the types of reasons split cleanly apart. One is a business decision to end activities, two are discipline violations, and one is health.

What’s interesting is that in the two discipline cases, the granularity of the announcements is inverted. OS☆U wrote only “rules violation” and withheld the substance, while Nanairo ∞ Milky Way spelled out the fact as “private contact with fans.” The former prioritized protecting the member; the latter prioritized signaling the rules of the scene. Neither is straightforwardly correct, but in terms of fans feeling satisfied, the latter leaves fewer questions hanging.

And the Payrin’s approach – announcing the group’s ending and the members’ paths forward at the same time – has been growing more common. It does more to protect the mood on the ground than dribbling information out in pieces. Isn’t this the result of a scene that spent 2026 in a run of breakups learning the etiquette of making these announcements?

October 2026 underground idol lineup changes: the summary

Here are the key points again. Payrin’s will end its group activities following the solo concert marking two years of its current lineup at BLAZE GOTANDA on Saturday, January 23, 2027, and Uta Yukimori, Piyori Suzushiro and Hinata Matsumoto will end their idol careers as well. At OS☆U, Kayo Tachibana departed and suspended activities effective October 13, 2026 over a rules violation, and the group continues as a nine-member lineup.

At Nanairo ∞ Milky Way, Haru Miyai departed on the same date over private contact with fans, and her X account has already been deleted. At Shirokumind, Nagisa Hoshine graduates and also leaves her agency following PANDA MUSIC FES mini vol.2 at Shinjuku DHNoA on Thursday, October 15, 2026.

Details of Payrin’s final live show, what comes next for OS☆U’s Kayo Tachibana, and any response directed at the fans involved in the private contact are all subjects on which there has been no official announcement as of October 2026.