UTC+9 is Japan Time. Very convenient for me
It's probably listed that way because LINE is a Japanese company, and they're a big part of Skullgirls Mobile.
UTC is a little annoying to convert to American and most European times because America switches between EST and EDT.
During the Summer, New York is UTC-4, so it's 13 hours earlier than in Japan (UTC+9)
I did a long distance relationship to someone in NY for two years, so I got used to doing it in my head. Take whatever time it is now in New York (2pm) and flip the am/pm (2am), then add 1 (3am)
So if it's 2pm in New York, it's 3am in Japan.
Also a handy tip: Install FoxClocks on your browser. It lets you add a bunch of different clocks to the bottom of your browser. I have East Coast, West Coast and UK listed down there for easy checking!