Meaning of 貸し and 借り in「この貸しは借りになることなく相殺もしない」


From chapter one of 転校先の清楚可憐な美少女が、昔男子と思って一緒に遊んだ幼馴染だった件

[![fig1](https://i.stack.imgur.com/V7s3S.jpg)](https://i.stack.imgur.com/V7s3S.jpg)

I have difficulty understanding the meaning of 貸し and 借り in this panel,
especially in this line

> この貸しは借りになることなく相殺もしない

Based on what I know. 貸し means something like "loan" and is used from the
perspective of lender. 借り also means "loan" and is used from the perspective
of borrower. It is similar to the difference あげる and くれる. But I can't apply my
understanding on the sentence above.




Usually, 借り is used to mean something you owe someone. It doesn’t have to be
money. I can be a favor or something.

> 君にひとつ借りがある。  
>  I owe you one.

The same thing can be said as 貸し from the opposite angle.

> 君にひとつ貸しがある。  
>  You owe me one.

However, it seems these words are used in a twisted way in your manga, like
when one person makes the other person angry or something, the second person
gets the right to “pay back,” and that’s called 貸し from the viewpoint of the
first person. The girl doesn’t get to pay off those “debts”.

