The narrator has never met Iida before, but he knows him by reputation. Iida has no idea who the narrator is, except that he is one of a group of people he is determined to destroy.
Even though they are strangers to each other, these characters are bound in a conflict of control:
Takeo wants to live; Iida wants to kill him and all others like him.
They can't both have what they want, so the conflict will carry on through multiple confrontations until one defeats the other.