My Stepmom's Daughter is my Ex Volume 1 by Kyosuke Kamishiro

[UDON Entertainment] "They’ve just broken up and become EX-boyfriend and EX-girlfriend, but now they have to live under...THE SAME ROOF!? Even though they still have feelings for each other, this EX-couple become SIBLINGS due to their parents' marriage!! Fall in love with a couple who constantly BICKER, but can't resist each other in this intensely-sweet and tantalizing romantic comedy!"