Seven adopted siblings in a wealthy Tokyo family discover their true origins after 15 years. The eldest, Arata, struggles with love versus family duty while living luxuriously in Seijo with his talented brothers and sisters.
After Kotono confesses to Arata, family dynamics shift. He tries maintaining boundaries while she pursues him. Seiha tests him with her own advances, unexpectedly stirring her feelings. The family faces changes as relationships blur.