She didn't join Hestia's familia in the SS, but Astraea told her to convert familias in it, and she thought of Hestia's familia so she most likely will convert during volume 19.

@Kisaki Tosane So probably ryu had joined the hestia family. At the moment there just wasn't the scene of her getting together. thanks

The chances of joining are very high no one leaves the city to find her deity just to help someone, and on top it the person was located far away.

I really want ryu's entry into the hestia family to be confirmed soon. I'll wait