Junta lives with his heavily pregnant wife, who is about to have their first child. Her older sister Akari comes over to help with the housework. Unlike his childish, selfish wife, Akari is gentle, mature, and irresistibly attractive, and Junta quickly becomes infatuated with her. After the healthy baby is delivered safely, Junta and Akari celebrate at home with a drink. Akari gets drunk and mistakes Junta for her own husband...