Board Thread:Questions and Answers/@comment-36.77.54.212-20151025114527/@comment-28053036-20151025115310

As long as you clear the same map's boss node 10 times, it will trigger the kebiishi to appear in that map.

The only thing you should care about most is the average levels of your swords. Kebiishi level will follow your highest sword level in the team, so if there are swords with big level gap, they won't be able to clear kebiishi effectively. More info here: Kebiishi