Here is Chimata's profile that explains the plot
Spoiler ahead
>Stage 6 Boss
>God of the Unowned
>Chimata Tenkyuu
>Species: God
>Ability: Capable of letting one relinquish ownership
>For humans, letting go of things is difficult.
>Even if you give it to someone, the information that it was a gift from you will remain.
>Even if you throw it in the trash, or illegally dump it on a mountain, the information that someone left it there will remain.
>Relinquishing ownership is no easy feat.
>However, there exists a place where that act can be perfectly carried out.
>The one place where people can exchange objects: the market.
>By selling something at a market, you can completely give up possession of it.
>She's a god who governs that act.
>These days, the buying and selling of things has come to occur without a market's involvement much more often, and as a result, there is an utter glut of ownership rights. She lamented this fact.
>When Iizunamaru came to her and asked her to open a marketplace, she knew there was no way she'd let this chance slip by.
>She replied that she'd cooperate with her if, and only if, the transactions took place under strict conditions, like those of the original marketplaces.
>She understood full well that Iizunamaru was taking advantage of her for a business endeavor.
>She was fine with this, because she thought that once the endeavor succeeded, she'd have already regained her power as a god and would have nothing to fear from a mere Great Tengu.
>The first market was held on the mountain's peak, as a rainbow encircled the moon.
>The only participants were Chimata, Iizunamaru, Tsukasa the kuda-gitsune, and Momoyo the oomukade.
>In that first market, they bought and sold cards with their own abilities sealed inside.
>Beneath the lunar rainbow, the four of them exchanged cards back and forth.
>Just as they'd planned, the replica abilities sealed in the cards completely detached from their original owners, and became part of their new owners' abilities.
>Both Iizunamaru and Momoyo were greatly excited by this result.
>Many more markets were held after that, and the cards spread far and wide out from the mountain.
>In order to use the cards' abilities, they had to be purchased according to the rules.
>Stealing, discarding, picking up, or receiving them wouldn't work.
>Those were the rules put in place so that Chimata, the market god, could obtain power.
>Iizunamaru thought of the markets as pure business, but for Chimata, they were a ritual of worship for her to regain her divine strength.
>When friction began to openly develop between the two of them, a force of destruction that would end it all arrived.
>She called that force of destruction a "robber"-- the so-called destroyer of the market, who tried to solve things through violence.
>Strangely enough, that human "robber" arrived on a night when a rainbow encircled the moon, just like their first market had.