The Best Canada/Japan Phone Option

So, here's the scoop. As of right now I have a cheap $50 flip phone on a Canadian phone-carrier. I want a new phone, but I will going to Japan in August for 6-12 months on a Working Holiday Visa.

So, I guess the question is, can I get an unlocked iPhone in Canada that is compatible with a phone company in Japan? If there is such a phone, the company's policy would also need to allow the activation of phones from other carriers. Is there such a phone + carrier that are compatible?

Any advice would be greatly appreciated. Thanks!

Here's an update, I think I might have somewhat of a plan but it is still incomplete. I will buy a SIM free iPhone5s model A1453, and get a wifi sim from bmobile in Japan.

Does this sound good? Is there any apps I could use to text over wifi in Japan? I hear a lot of Japanese people talk about LINE. I would really like it if I could find an app that allowed me to get my own number, and text other numbers whether they have the same app or not.