So-jin comes to believe that the kind of food she and Yeon-woo consume will play a big part in their relationship, so she works hard to make Yeon-woo eat similar food. After learning her intention, Yeon-woo invites her to his place to cook a meal for her, but things don't go as expected. Meanwhile, Kang-hoon tries to find the cause of the fire that killed Ha Ga-hee, Yeon-woo's father's mistress.

It turns out So-jin has the BRCA gene, which makes her more likely to get cervical cancer. She ends up getting enteritis from the food she had at Yeon-woo's, and Yeon-woo decides to operate on So-jin himself. So-jin contacts her mom and sister to ask them to come on the day of her operation, but both of them refuse, leaving So-jin with no option but to be without a guardian.

Even after So-jin starts dating Yeon-woo officially, she can't let her guard down because of Yeon-woo's Indecent Octopus Tentacle Gene. Mi-eun visits So-jin's office for a consultation and ends up giving her a tip on dating Yeon-woo. So-jin decides to start a project to improve Yeon-woo's genes. Meanwhile, Yeon-woo's parents decide to get divorced.