No, there is a limited number of prizes for each group, which can only be given by your leader when the final results are out on Saturday. You can check how the prizes are distributed by checking the distribution record when you talk to the staff of great ninja war.

Overall it's a guild event that will result in a lot of players giving their time for nothing... Since there will be so few reward .... (A few coins and contribution... Ain't all that interesting, unless lucky enough to get one of these box...)

you get normal rewards too though
to use at the group store

or if your leader is well organized, you guys will probably take turns with the prizes