In the sweltering heat of midsummer, Hisashi, having failed in his job hunt and emotionally distanced from his family, finds himself sinking into despair. Amid his growing darkness, he begins to develop romantic feelings for his stepsister, Taiichika. His emotions intensify each day until he finally forces himself on her. Though she resists, Taiichika's heart begins to waver when he whispers, "I love you." Their forbidden passion deepens, culminating in sweaty, intense encounters in the suffocating heat of tropical nights. The conflict between raw desire and love between them burns like an uncontrollable flame.