"Nari, falling in love is easy, you just need the right formula" Oh Nari and Jeon Jungkook have been best friends since the day the both of them were born, they were inseparable twins, two peas in a pod. But when adulthood comes, childhood years fade away, and a new girl replaces Nari's spot in Jungkook's life as his most important girl, their bond slowly drifts apart. And both end up hurting each other. Will they be able to find the right formula to bind their hearts together back again?