Akifumi Chizu’s mornings always began with his sister’s lips. When he woke up, they were usually just a few centimeters away from his own, and the first thing he’d do was skillfully evade them. It had become a daily ritual. His sister, Akane, two years older, would smile softly and click her tongue as Akifumi used his pillow as a shield. With her refined features and long, flowing black hair, Akane was the picture of a traditional Japanese beauty. Her graceful demeanor made her the talk of the neighborhood, but she didn’t have a boyfriend. Why? Because Akane was utterly devoted to her little brother. “Come on, get out already,” Akifumi said, pushing his sister’s back and pushing her out from his room. He let out a deep sigh… Around the same time, in another household… A man named Kouji Awakura was struggling, his neck caught between the legs of his older sister, Miyako. Tasked by their mother to wake Miyako up, Kouji had approached her bed and called out to her—only to end up in this predicament. Miyako, still half-asleep, mumbled incoherently as she tightened her thighs around Kouji’s neck. Finally managing to free himself, Kouji looked up at his sister, who was now stretching lazily. He couldn’t help but stare—Miyako wasn’t wearing any pajamas, and her small but well-shaped breasts glistened in the morning sunlight. When their eyes met, Miyako called him a “pervert” and kicked him out of her room. Kouji fled like a dog, though his arousal was unmistakable. …… These two pairs of siblings, though different in their dynamics, were just your typical close-knit brother-sister duos. Or so it seemed… “Honestly, having brothers is such a pain,” said Oohara Maya, a mutual friend who also had two younger brothers. “Taking care of them is exhausting.” “Yeah, from morning till night… it’s too much for me to handle,” one of the sisters replied. Maya’s words sparked a change in the atmosphere. “Wait, what do you mean, ‘too much to handle’…?” “Uh, are you saying…?” “Well, it’s obvious, isn’t it? We’re men and women, after all…” At that moment, Maya should’ve noticed something. The two sisters sitting on either side of her, who had been joking around just moments ago, were now lost in thought, their expressions serious. [Translated from dlsite]