Two people who don't get along became a lovey-dovey couple overnight?! "Scarlet Night" is a secret organization that undertakes national missions. Juntaro and Iris, who are renowned as the strongest in the organization, are on bad terms and always fight whenever they meet. Though, in reality, the two are attracted to each other and are both suffering from an unrequited love. However, the two are adamant on never admitting their love for the other. But one day, they are ordered to pretend to be a married couple for a mission to protect the princess...?! What will the two do? The most difficult mission begins now!