User blog comment:Dragonjet/KC3改/@comment-26107337-20150921020538/@comment-1820055-20150924013201

sorry, we cannot implement this, by chrome limitation. it does not allow muting of specific tabs only, unless chrome hack-arounds are involved.

you can specifically make your chrome get the ability to do tab-muting though, which may also be useful for your other non-kancolle tabs:

http://www.omgchrome.com/how-to-enable-tab-mute-chrome-feature/