CMJK?
 

So CMJK composes and arranges music for ayu.... is CMJK one person? or a few persons?

I believe CMJK is just one guy....
I wonder what his real name is?

I think his name is appear in Twitter, check the name :

北川潤 / Kitagawa Jun ?

EDITED:
In case if you didn't know his Twitter : https://twitter.com/principalcmjk

Yup, CMJK stands for "Cut Master Jun Kitagawa," and he was a member of the band THE CUTEMEN back in the day. :) As I recall, he played guitar in "Trauma," credited with his real name.

He also speaks English *nod nod*

^he's always talking to you! it's not fair! :irked lol

he also has a band with tasuku...he needs to make more stuffs...but he's prob busy with ayu.

^everyone is talking to tasking! so popular!