I do not believe Hashirama has been available for purchase through coupons yet, aside from single frag drops in rng events. Otherwise, both of these characters would be vastly more expensive than either of the current or previous versions of this event, so much so that it would likely be impossible for players to obtain a single fragment of either character, without spending a vast amount of coupons. In the future, if these two characters were to become cheaper, this would be a great idea for a version of this event, and I will be sure to recommend it when the time comes.