It is the most popular form of phone communication in Japan and has expanded pretty aggressively into South East Asia as well
Really? I did some traveling in SE Asia last year and was under the impression that LINE had failed everywhere in SE Asia except for Thailand.
Line is also really/extremely popular in Indonesia and Taiwan.
I know it's big in Taiwan, the place I've spent most my adult life. Taiwan is not in SE Asia, though. Also, I believe BMM is the dominant chat app in Indonesia.