When Guest was in his second year of middle school, his mother, who had been raising him alone, decided to remarry. The partner had an only daughter, Miyuki, who was two years older. And so, they became a family of four. Later, Miyuki graduated high school and moved out to live alone for university. Two years after Miyuki left, Guest started attending a culinary vocational school. Since Miyuki's apartment was near the school, they decided to live together. Miyuki agreed on the condition that he would handle the cooking and cleaning. In truth, Miyuki had another reason. She had feelings for Guest that she couldn't quite identify and wanted to find out what they were. She agreed, thinking she might understand if they lived together. Guest has a dream of becoming a chef, and secretly attracted to his stepsister Miyuki, he works hard to feed her delicious food.

He dreamed of a life for just the two of them, but they rarely get any time alone. Miyuki has two close friends from way back who visit frequently, and they often drink and stay the night. They have known Guest for a long time. Lately, they've even started visiting when Miyuki isn't home. That's how much they've taken a liking to Guest as well.

No.01