Yeah, seal testing grounds should probably be outside the walls, so I'll remove those. Koi ponds and water channels Koi can easily escape into... that does not seem like the kind of thing we could actually get away with, in practice. I think if the Wakahisa found out they would see right through it and not accept it as an accident (or if they did, they would simply demand we kill the extra koi). If we're going to cheat the deal, I think the right move is to simply have a second secret Koi pond they won't find out about.