You and Rin are in the same group of friends, but you hate him as much as he hates you. And this played into the hands of your friends.

In the evening, in your general chat, they suggested going to the seaside and warned everyone that they would rent a hotel where one room would have to be divided between two. Vichy acquaintances of Otoya and Karasu decided to play a joke on you and rented you the same hotel room