TELL ME YOU'RE LYIING OMG WHERE ?? I'm French and I've only found the two first volume from Hana collection on boys-loves.fr
I think I just bought it from Fnac, if I remember it correctly? They're all from Hana collections but the last two are seperately numbered: Canis- The Speakers, and there you have tome 1 & 2 again. I just checked and Fnac currently still has all 5 for about 8 euros each.
Also, the third volume is 'dear mister rain' so by searching dear hatter you won't find it, just look op 'canis manga' and you should find all 5.
If you guys live in Belgium/France you can also buy it from a French publisher, they have the first 5 volumes already and it's much cheaper than trying to find something English here!! (Though I would rather read it in English, but it's easier to support the author like this.)