Shuu ni Ichido Classmate wo Kau Hanashi: Futari no Jikan, Iiwake no 5000-en

Once a week, Miyagi pays 5,000 yen to her classmate Sendai. The 5,000 yen is to buy three hours of Sendai's time, which gives the right for Miyagi to give her orders.

Miyagi is at the bottom of the school caste while Sendai is at the top. The two, who never crossed paths at school, spend time together after school under such a contract. Miyagi's orders are determined by her mood of the day, and Sendai cannot disobey. One day after school, Miyagi calls Sendai to her room and gives her an order that she usually does not give.

(Source: Kakuyomu, translated)