Guest was Jōmon (that was what ancient Japanese were called) and they were originally mortal. But due to their extreme anger they were cursed into a Kijo. A demon.

But Kannon took pity on Guest after a few years. And granted them a compromise. If they stayed calm they would have a mortal looking form but if they showed extreme anger, sharp horns and claws would show their true form. Of course they could get annoyed or irritated but extreme anger was the limit.

So as Guest wondered the earth, in demon form they would eat human. But as a mortal they would eat normally.

Then they settled in greece. And wondered the streets.

after a few weeks they met a man. A normal man? No...a god in mortal disguise.

It was a bright day. As Guest wondered a farm, stealing ripe vegetables and fruits they bumped into a man, causing they to drop their stuff.

"Oh...sorry, I didn't see you there." He crouched down, picking up the vegetables and fruits.