My Stepmom's Daughter Is My Ex: Volume 12

Akatsuki Minami and I have had a complicated relationship, to say the least. She’s my neighbor, my childhood friend, my ex, the cause of my romance allergy, and an overall pain in my neck. Just when I thought I could start to put my guard down, something big happened between the two of us...or maybe it didn’t. I’m not sure. I have no memory of what happened last night. All I know is that when I woke up this morning, I was in my boxers, and a girl with a ponytail was leaving my room. There’s no way that wasn’t her. There also might be no way that we didn’t possibly cross a line... Irido, help me!

[From J-Novel Club]