Line is one of most common communication APP in Japan that basically you can chat, phone call, and video call etc. If you have any plans to study and work in Japan or looking for Japanese friends, this is one of the best communication tools there. The way to use this APP is almost the same as “WhatsApp”. So, they are not complex to use.
Normally, when I ask the contact to others, I always ask for a LINE account ID or QR code. From my perspective, it is easier than asking them a phone number and you do not have to memorise your number.
But, in the business situation, they may ask you to have a number or e-mail address. Once you master these things, now you are ready to have some drinks in Izakaya.