It's not from Korea. It's by the Japanese subsidiary of the Korean company. You can _technically_ say it's Korean, but it really isn't.
By the way, I'm a Korean.
Were you born in S. Korea?
It is quite suspicious though. A Korean company makes a messaging app used by Japanese people.
Line may well be a spying tool. I'm pretty sure Korean would like to keep tabs and eavesdrop on Japanese.
It's actually started by a Japanese subsidiary of Korean company; LINE corporation (which used to be Navar Japan), but I'm pretty sure its parent involved quite a bit, so I guess it can be considered from Korea...