But the childhood friend was obsessed with the MC and had feelings for him like a dog, while the MC eventually killed him and took his girl like a scum. I think the title is clever because it could apply to both of them.
Why is smacking someones hand always so dramatic in manga. If someone did that in real life i'd just think their reflexes kicked in and move on with my life.
FWIW I saw someone talk about a white guy going to Japan and the girl he was with was like noo noo and he stopped and she got really confused. I think there might be a cultural thing there, but that's just second hand information so who knows.