Konflik memuncak ketika orang tua mereka pergi bepergian dalam waktu yang lama, meninggalkan Mizuki dan Yui sendirian di rumah. Dalam situasi ini, dinding pemisah antara "kakak-adik" dan "laki-perempuan" mulai runtuh. Yui mulai menunjukkan sisi yandere (obsesif) dan agresif, memanfaatkan situasi untuk mendekati Mizuki. Pertanyaan besar yang melayani judul serial ini— "Tidak mungkin cinta pertamaku adalah kakak kandungku sendiri" —perlahan-lahan berubah menjadi kenyataan yang tak terhindarkan ketika kedua karakter tersebut menyerah pada hasrat mereka.

The nostalgic, unfulfilled longing of childhood love colliding with adulthood desires.

is a prominent Japanese adult animated (hentai) OVA series originally released on December 24, 2021 , and produced by the veteran studio Mary Jane . Translated roughly to "Sister Hookup: There's No Way My First Love Is My Real Sister," the franchise spans across light novels, manga, and animation. The 2021 adaptation firmly cemented the title within the "forbidden romance" and "misunderstood lineage" subgenres of adult anime, captivating fans with its high-quality production values and complex, dramatic narrative. Narrative Architecture and Plot Dynamics

As documented in character profiles on IMDb , the voice cast features genre staples such as Ayane Kizaki voicing Shirayuki Nana, bringing the necessary emotional weight to a story that balances explicit adult encounters with genuine melodrama. Over its two episodes—concluding with the second part in April 2022—the narrative moves from simple domestic tension to an explicit exploration of their shared past and crossing boundaries. Structural Analysis: The Two-Part Format