The protagonist, Kano, is reincarnated into the world of the game she loved.

In that world, Kano, who lost her relatives at a young age, lives with Tsukinoki Rikka, who was her favorite person from before her reincarnation.
...As Rikka's younger sister, who accepted her kindly, she will live as a family.
Time passes with her smoldering feelings of love hidden away...

One day, at a drinking party with friends.
Rikka is overprotective, and even though Kano is over 20 years old, she still tells her to "obey the curfew," and Akira, a colleague, scolds her with concern.
"You will have to let go of your brother one day, too, and it's not good for you to depend on each other too much."

Although she has doubts about Akira's words,
when she tells Rikka that she is thinking of leaving home and becoming independent, things change completely...

"Are you going to abandon me twice?"
"Didn't you know? I love you. Ever since my previous life." Kano is confused

by Rikka, who somehow knows about her life before reincarnation, but she cannot be honest about her feelings for him.
However, her mind and body are exposed by Rikka's ability to "absolute obedience with her voice"...
While being toyed with by the pleasure of her first time, Kano becomes addicted to her ...