A webpage discussing a Japanese kabuki magazine:
"Also in the issue, among other features, are discussions with actors Nakamura Kazutarō, Onoe Ukon, Nakamura Yonekichi, and Nakamura Hashinosuke about their then upcoming March program at Kyoto’s Minami-za, focused on these rising 'young stars' (hanagata)".
Quote from a book on film and acting stars throughout the world:
"...the kimono and ornamental hairpins (kanzashi) that kabuki stars (hanagata) were wearing...".
A 1940 article titled "Kansai de chûmoku sareru hanagata kabuki", which was translated as "Young stars' Kabuki in the Kansai Area".
A 1883 woodprint with a whole cast of actors that is titled "Arigataki megumi no hanagata", which translates to "Kabuki stars at a blessing waterfall". I mean, if this isn't plural I don't know what else could be:
I could search more if you want. We could debate whether the word is grammatically plural itself or not, which is more of a linguistic debate (for example, "people" in English is plural but "gente" in Spanish is singular, yet both refer a collection of individuals). But it's clear that "hanagata" can be used to refer more than one person.
Here above I share some examples.