He contributed nothing.
I pray it is because he is so busy working on music of his own that he simply had no time to come up with something to add to this song.
I was waiting for the Mana part up until the last 30 seconds when I knew it was already too late.
You didn't think the first bit at 0:34 to 1:03 was right out of the M10M playbook?
I also agree with
@Phantom Pabulum that there are some M10M-styled riffs in that one "shouty" section, as well as those scattered harpsichord flourishes. I mean, considering Mana didn't actually write the whole song, that's decent representation when there are 4 bands and a bajillion members waiting for their spotlight.
And yeah, I can't unhear the "Attack on Titan" thing now
On the whole, Kamijo's melody was catchy but the song as a whole was just a grab-bag of styles, as it inevitably had to be. Maybe it would have been more interesting if they did a whole collaboration
album where they could do a more measured blending of styles. But you know, who's got the time...
Whoa whoa whoa, what are you saying?! Weren't you at Christmas Party 2013, Christmas Party 2014, Christmas Party 2015...
I'm starting to fear Mana has some terminal illness and that is why he's being throw so many bones by these other bands.
Nah, I'm afraid it's something worse than that. It may well be that he's got what every true musician dreads:
a job.