"Kaguya-sama: Love Is War" follows a clear evolutionary path from comedic battles to sincere romance and external conflict. In Season 1, the plot is driven by the episodic 'battles' of wits, culminating in the Fireworks Festival, the first major crack in their prideful facade where Kaguya admits her loneliness and desire for connection.
Season 2 deepens the character backstories significantly. The focus expands to Yu Ishigami, revealing his past trauma from middle school where he was ostracized for defending a classmate from her cheating boyfriend. Miyuki is revealed to have been the one who saved him, cementing Ishigami's loyalty. The season ends with Miyuki accidentally seeing Kaguya's vulnerable side after she falls asleep, a key moment that humanizes her in his eyes.
Season 3, "Ultra Romantic," is the turning point. The entire season builds towards the Hoshin Culture Festival. Knowing he will be leaving for Stanford University soon, Miyuki decides to confess. He creates an incredibly elaborate plan, framing his confession as a grand 'theft' of Kaguya's kiss. In the finale, he succeeds, leading them to share a passionate kiss atop the school's clock tower. This event effectively ends the 'love is war' premise, as they have mutually confessed.
The movie, "The First Kiss That Never Ends," explores the immediate, awkward aftermath. Their lack of a formal verbal confession throws them into confusion. Kaguya's psyche fractures into different personas—her cold 'Ice' self and a childlike 'Little' self—representing her fear of commitment and her desire for a perfect romance. Miyuki, in turn, must confront his own insecurities, realizing he doesn't need to be perfect to be loved. The film concludes with them achieving a more stable understanding and truly beginning their relationship, marked by a second, more intimate kiss. The overarching narrative reveals that their initial 'war' was a necessary, if immature, way for two emotionally stunted geniuses to navigate their feelings until they were mature enough to embrace vulnerability.