Bakuhatsu Sunzen!! Tenshi no Countdown

Motoki, a high school boy, faces a chaotic domestic situation. His older sister Megumi is in a relationship with Eika, and their intimate encounters are frequently loud. Eika, who is bisexual, often provokes Motoki and sometimes seduces him, leading to heterosexual interactions. This behavior distresses Megumi, who worries about her girlfriend's attention shifting to her brother. Additionally, Motoki's friend Yuji, who is gay, persistently pursues him despite Motoki's stated orientation. Emi, Yuji's sister and a friend of Megumi and Eika, is also bisexual and engages in teasing Motoki. Amidst this, the possibility arises that Natsuki, who appears more reserved, might offer Motoki a different dynamic.