Kingohgers: Iroki and Karas transforming aaaaaaaaah!
Also Rinna's actress became a sentai before she became a Rider lol despite appearing first in Rider
I literally screamed when Karras planted the sword into the ground and said the henshin phrase aaaaaaah
And Iroki became the first female black ranger in Sentai history to boot
Though, Rei Yoshii wouldn't have been the first KR actress to jump into Sentai and become a hero there. Mio Kudo did that, too- she was just a civilian during her appearance as Kanon in Ghost, then became Sayo/KirameiPink when she joined the cast of Kirameiger. It was only later when she reprised her role as Kanon in Blades x Spectre that she became a Rider. So, who knows, maybe Rinna gets around to making herself a Driver by Drive's 10th anniversary this year
Heck, if we're counting actresses who were cast as one-offs, then Ichika Osaki counts too- she played the victim of the week in Zi-O (funnily enough, it was the Ghost tribute), then she got cast as Asuna/RyusoulPink. It remains to be seen whether she eventually gets cast as a Rider lol