So there are women only subway cars in Japan to help prevent groping on the train. So porn started having stories about secret cars for being groped.
It's led to a Japanese porn trope of cars secretly for a given fetish. Usually the main character accidently gets on the car not knowing and learns to like it. It's similar to the "how do we pay for the pizza?" trope.
Barring the barely disguised conversion fetish, the one about the straight girl walking into a lesbian mixer is actually a cute story.
There's another manga about a college student and a bus driver with a similar premise (different author, forgor the name 💀); that one's also really cute.
It is. For me, it isn't the conversion that's cute, but the self discovery. I relate heavily to the whole "stepping out of your lane only to actually find where you belong."