Pls help I forgot the name

I’m looking for one, I think it was Korean manhwa. It’s set in zombie environment. Top is unable to feel emotions since he was a kid, I remember he was really good at sports, I don’t remember if it was judo or taekwondo. He ends up meeting the bottom when he was ditching a group of people. Bottom always carries a suitcase with wheels that his parents got for him and has photographic memory. They somehow end up getting together but before they get to the shelter this random dude ends up getting the bottom bit by a zombie and bottom ends up telling Top the location of the shelter. Top gets there and his sister is apparently a doctor there and they end up finding the bottom and saving him. I think at some point they passed by an area where it was like a kindergarten?? An exmilitary man and two orphans lived there.