This "Great Spirit" better be ready to accept her new position in life.
Emergency Ration with a side of EXP/Ability Boosting when consumed.
Also hot damn Erofu Mama with Underboob and easy flaps to access the mamaries humina humina.
And with a little kusogaki imouto tsundere flat is justice on top of the deredere yamato nadeshiko girl next door Erofu medium is premium main waifu heroine...
So... Shimaidon and Oyakodon is on the menu?
...
On a more serious critical note, we still have yet to have any reason for this to be an Isekai, all his knowledge he's pulling is from within the fantasy world he's in and all his actions would still be in line with a naive fantasy protagonist. I really hope there's an actual reason for him to be an isekai protagonist and not just your run of the mill "And this is Katsudon! And this is the miracle of Soy Sauce! And this is advanced technology from modern day Japan, such as Paper Printing! And now I will work extra hard to make sure I don't live a black company life! And now I will make the ultimate fantasy weapon, a Katana and/or Gun!"