http://www.helloproject.com/news/8741/(focusing on two former MM OGs coming back to H!P after 18 and 12 years respectively)
8/4 & 8/5 - Ichii Sayaka (with Yasuda and Yoshizawa). Guess that's the Pucchi Moni ver 1.1 or 2.1. So close. Just needed Goto instead of Yoshizawa.
https://www.instagram.com/p/BkCqcp0FsUS/ (Ichii)
8/25 & 8/26 - Kago Ai (3 shows)
https://twitter.com/lovbus/status/1007554238027665408 (Kago)
And guess there will be some crying, maybe. Definitely Kago. Not sure how Ichii would react if she gets cheered on at H!P concerts after all these years.
Now if you think about it, while there is no reason for UF to pay them to come back, there is also no reason for them to completely media-ban them more or less after all these years (after 2 years or so to let things cool down). Not like they committed major crimes and spent time in jail or something.
Now after Ichii (last in 2000; left UF in 2003) and Kago (last in 2006; fired in 2007), this would leave JunJun and Kamei as the former MM OGs without UF-related jobs the longest (7+ years and counting; since 2010). LinLin appeared via a taped segment for MM TV appearance once while Michishige was still around, if I recall correctly.
But Fukuda and Ichii were the big ones as they were out of UF for so long while Kago had that unfortunate history. At least all these 3 girls (or women, as all of them over 30s) have been active in show business (in Japan), so there was a chance.