Kisee (किसी) and koee (कोई)
Since there are no tips and notes for the Convo skill, I'll share this:
Good description of how to say someone/somebody/anyone/anybody/no one/nobody and when to use किसी vs when to use कोई can be found in a youtube vid embedded in this web page: https://www.hindicentral.com/कोई-and-किसी/
Long story short: they mean the same thing, but you use koee when there's no postposition involved and kisee when there is one. Watch the vid. A little under 10 minutes and well worth it.