...the joke hasn't been translated well, it seems. IIRC, the subject/object of a sentence can be implicit (i.e., inferred from context) rather than explicit in Japanese (cf. Latin verbs). Kurosawa's statement in pg.4 should probably be rendered as "...do I not even have a chance as long as Onee-san is around?" This removes the critical "you" that makes the MC look like he has an IQ of 40.
But take all this with a grain of salt, since I do not read/speak Japanese.
Though to be fair, anyone in that situation who wouldn't have an inkling of what Kurosawa is really saying probably does have an IQ of 40.
@justforthelulz
rom-com protags have to be as dense as a neutron star so the author doesn't have to think about crazy shit like "character development" or "plot progression"