"Your heart deserves to be treated as gently as everybody else's"

South Korean Kim and Italian Alessandro have been working in the same building for years and fighting an endless prank war.

Alessandro is messy, oversleeps, drinks too much and enjoys making the downstairs tenant miserable. Kim, the downstairs tenant, runs an Italian language school and a tight ship. He suffers no fools, especially the fool in the science lab upstairs.

When they agree to meet to celebrate their "rivalniversary," they begin to see a side of one another they weren't expecting, and on the shore of the Mediterranean Sea, their rivalry turns into friendship... or perhaps it's the start of something just right.