Yuu's Yandere Awakening!? The Secret Cohabitation Life Begins with the Two "Onee-samas" She Admires! The top star of the opera club and a friendly (actually yandere) "onee-sama" Shirazaki Yuu, along with her twin sister and excellent student council president (actually socially awkward) Shirazaki Hatsu. Surrounded by these opposite twins, Kusumori Sugara's daily life is drifting further away from peace!? To be recognized as the "Engage Sisters" by everyone, Yuu and Sugara are set to perform in the Tanabata Star Festival. However, during practice, Yuu suddenly loses her voice. While Yuu is recuperating, she secretly plans to switch places with Hatsu, and their shared life begins. As Sugara gets flustered by the twins' approaches, she improves her acting through practice with Hatsu. Yet, watching this unfold, Yuu's heart begins to swell with a certain feeling...