Cuckolding is inevitable! A classroom where you cant leave without xx [RJ391800] [hijoguchiyuki]

Two people are living in an extraordinary situation within an ordinary town.Takahiro and Yumiko were born and raised in a family of exorcists.The two are childhood friends and partners, but due to family circumstances, they become engaged.They were aware of each other's feelings, but their relationship was to remain pure until they finished their studies.The two of them were tasked with protecting the town from supernatural phenomena on a daily basis.Following their assigned duties, they track down the traces of the strange phenomena that have recently been causing trouble in town.The two finally corner the demon that is the source of the strange occurrences.However, in the demon's last desperate struggle, the two are trapped in a place that resembles a school.It was an alternate dimension from which you could not escape unless you completed the challenge.Furthermore, Ren, the younger brother of the school's chairman, Takahiro, also gets lost in the situation...