Reborn As a Character That Never Existed

“After meeting her death, Thalia is reborn as the female protagonist’s older sister, a character that never existed in the novel she wrote in her past life.
She tries hard to get attached to the world inside the novel, but she gets caught up in the thought that everything is just a mere creation of her own.
“Please make Tilly love me.”
Aegis, who was supposed to fall in love with Thalia’s younger sister, makes a wish to God on his coming-of-age birthday.
Will Thalia be able to love Aegis?”