SPOILER ALERT: the following article contains massive spoilers, including the ending. If you have not yet seen the movie, proceed at your own risk, or better, come back to this article later!
SPOILERS AHEAD
Kaguya-sama: Love Is War – Final Plot Summary and Synopsis
Student council president Miyuki Shirogane and vice-president Kaguya Shinomiya appear to be the perfect couple. Kaguya is the daughter of a wealthy conglomerate family, and Miyuki is the top student at the school and well-known across the prefecture. Although they like each other, they are too proud to confess their love as they believe whoever does so first would lose. The story follows their many schemes to make the other one confess.
Source: Wikipedia (CC BY-SA 3.0).