Board Thread:Questions and Answers/@comment-33183866-20171017025137/@comment-31661832-20171017031221

Kais are more common than you might think. There are probably 10 or so in the Baba Shop from various events, there's a summon that gives you 10 kais that spins around every major celebration, and the mono banners (like the ones running now) give 2 kais per multi summon.

They are still rare enough that you can't just spend them on anything, but LRs are usually worth it.