When his older sister and her husband go missing after their plane vanishes, university student Yuuta Segawa becomes the sole guardian for their three young daughters. Fourteen-year-old Sora balks at trusting a virtual stranger, ten-year-old Miu tests him with mischief, and three-year-old Hina simply wants attention, all packed into Yuuta's cramped one-room apartment. This manga adapts the light novel of the same name, following the makeshift family's daily adjustments to campus life, childcare, and each other.