I'm the Strongest in This Zombie World, But I Can't Beat This Girl!, Vol. 1 — Ryou Iwanami

In a Japan that's on the verge on ruin, he's surviving alongside a cute underclassman! A sudden zombie outbreak ravages the country. Amidst the fleeing crowds, high school student Yuuma Kousaka ended up being bitten. Afraid of dying, he reunited with his friend's sister Haruka Hinata for the first time in years. She offers to fulfill his dying wish and be his girlfriend. And with that, Yuuma makes his best and final memory. But after becoming a zombie, he retains his consciousness! “I thought you were going to die soon, so I showed you my boobs! This wasn't the deal! You need to take responsibility!” And thus, a romantic comedy begins between Yuuma, the strongest boy in a world of zombies and Haruka, a girl who knows all his weaknesses.