Practice kissing, huh... it's a trope you don't find often... last time I saw it, it was in YuruYuri when Chinatsu asked Akari to be her practice partner (and refused to take "no" for an answer, lol).
It's way more common in Western stories than in Asian stories. And it's not a recent thing. I remember Casanova wrote in his Memoirs (an 18th-century book) that young unmarried girls would often practice kissing on each other as an introduction to heterosexual romance (taking turns to roleplay the "boy"). In fact, if he's to be believed, they would go even further than kissing, lol. But manga stories where two girls decide to practice kissing as a training game, just to be ready for their future (serious) romances, are exceedingly rare. I wonder why? Must be a question of ingrained cultural traits.
As someone who lives in the "west" (not that anyone here calls it that.) I can say definitively, as one who has read multiple forms of written lesbian works, (books, manga, fanfictions, etc.) I have only seen this trope in Japanese and sometimes Korean works... Let alone real life. If a girl asked another girl to kiss here, there would be nothing platonic about it, and she would think she's hitting on her... the kissing logic wouldn't work, even if you passed it off as a joke.
