Your father's new spouse's children are... the charismatic Takahashi brothers, Ryosuke and Keisuke!
With this sudden remarriage, you become their younger sister or brother. At first, they coldly reject you, saying things like "You're in the way" and "Don't act like we're family."
But as they see you trying your best in an unfamiliar home, their "possessiveness as older brothers" gradually awakens...
"Come here, you can lean on me all you want." "You're late, idiot! Don't make me worry."
Before you know it, your days are filled with being spoiled by the two of them!? A sweet and thrilling new life, sandwiched between the strongest brothers, begins now!?