As the title said, Nickelodeon South Korea has premiered this month the Season 5 under name of "Sirenix Power" (사이러닉스 파워 ).
The premiere date was on Monday January 7th at 1PM with brand new episodes 3 days weekly.
But, communly Nickelodeon South Korea hasn't an order in the premiere schedule, like other countries, so, it's impossible know when airs a BRAND NEW episode, only looking at the TV Schedule in the website.