Future Diary, Vol. 5

Via the scheming of his new friend Aru, Yukiteru and Yuno share an unexpected date at a free 'wedding trial' program. When they get back to Yuno's house, the room in which Aru expected to find dead bodies has been replaced by a giant hole in the ground. Not only that, but Yuno seems to have willfully tampered with her own memory so that she's forgotten that Yukiteru ever even visited her.