I actually buy the volumes on amazon kindle, you just need a japanese account (not related by to the western one) and change your address to somewhere in japan. Them you can just normally buy it by card.
i read this at a very short span of time and it was really sad and heartbreaking, i love the characters. It was worth the hurt and tears while reading this masterpiece.
just let this end like this pls no need the angst and fucked up plot i want them to be happy