In an infinite-flow S-grade dungeon, top assassin Chi Yu and mortal enemy Gu Yuan are forcibly soul-bound by the system. Unable to kill or betray each other, they must pretend to be a married couple in the Rose Manor to make the immortal flower, which feeds on "true feelings," bloom. Afterward, they turn into four-year-old toddlers barging into the Goldfinch Orphanage, stopping the centennial festival and uncovering the truth behind the disappearances. Once quick to try to kill each other on sight, they are now forced to fight back-to-back, shoulder to shoulder in the thorny corridors and chanting the wedding covenant together in the bell tower. While wanting to finish each other off, they have simultaneously become each other's only usable blade. Strong against strong, mutual love-hate, extreme tug-of-war between a madman and a cold-blooded killer—whether it is acting or genuine affection, even they cannot tell apart.