Now I understand the meaning of this story's name!! That's nice :)
Well, inferno means "a large fire that is dangerously out of control." And Hitoshi literally started a fire that will spiral out of control (also he's small and adorable). So I'm assuming the title would be Mayumi calling Hitoshi his Little Inferno.
Does that make sense? Sorry if it doesn't, I'm not good at explaining things :(











Now, this is epic