I'm not really sure its a Kaga thing. Binding Blade was done without Kaga and it has the same problem as Gaiden were most female characters you recruit have to be freed from a jail cell first. Doesn't matter if they're a sweet childhood friend, dragon loli, fierce warrior or a legendary witch that makes even Pent geek out. If you're a woman its down to the jailhouse with you. Kaga's Archenean and Jugdral series also divide the ''distress ball'' more evenly with the likes of Corpul, Midyale, Rickard or those bald general twins(they're twins right?) also having been kidnapped. And Gordin if you count the remake.