23

Goroawase

9th prime chivalric order

the 9th prime number is 23

23 in japanese wordplay can be read as ni-san meaning big/older brother

Therefore the 9th prime chivalric order is the big brother's chivalric order.

Meow refers to Miyao as her big brother and he has a chivalric order, the order of the public bath.

The order of the public bath is her big brother's chivalric order

9th prime chivalric order.