Chapter 1.2, third panel, third (or second and a half) text box: "It seems Tadashi is the man who is to be the savior of the world after all." <- this is not a mission. He is not telling Tadashi to be "the savior" he is expressing his pleasure that Tadashi chose him.
While I certainly cannot say that it is proven, as no one objects to the Agriculture God's words, there is evidence for this. No one agrees that Tadashi is "the savior" and the God of Wisdom and the God of Heroes immediately object to the number of stars that Tadashi has, willfully (directly and intentionally), been given. They specifically state page 3, panel 3, text box 1.5: "The maximum number of blessings you can bestow on a human being is five stars." These two only give up after the Goddesses of Beginnings states on page 5, panel 3 that: "The first reincarnation to receive the blessing of agriculture is Tadashi Ohno." and "If the blessings don't involve combat, seven Stars won't cause too much havoc." She, nor anyone else, even implies that he is "the savior."
So not only is he never told that he has a mission (only very briefly referred to as "the man who is to be the savior of the world" one-sidedly by the God who has never been chosen before), the other Gods initially object to him even receiving as much power as he is by the God of Agriculture. None of the other deities agree he is "the savior" and the God of Agriculture has to lay on the ground and beg for even a single star blessing from the others, except the God of Blacksmithing, who agrees to give two if he builds a shrine. Etc.
No. In fact, in researching my response, my original question was answered. On page 7, panel 5, the God of Heroes basically says "A God would seek to monopolize the incarnations of those with strong souls in order to increase his own divine power."
So, the reason this entire process exists IS to gain something in return: an increase in their divine power.
tldr: ONLY the God of Agriculture said he would be the savior. No other God or Goddess confirmed it. Two objected to the number of blessings, only agreeing after the Goddesses of Beginnings said it would be fine. They only gave him more (blessings, etc) when the God of Agriculture begged, or because they specifically got something in return, not because he has a mission, none of them agree he is "the savior."
