I don't think it is properly explained (at least not in the manga) but ch 29 Dark Dream implies that all intelligent zombies (or maybe all zombies) can communicate telepathically.Is mc just talking to himself or does he have a telepathic link to the neighbor zombie? Maybe his semen is a quantum entanglement communication device for those who are infected
In the VN Tokiko ending, that is exactly what happens with Tokiko and Yuusuke.I don't think it is properly explained (at least not in the manga) but ch 29 Dark Dream implies that all intelligent zombies (or maybe all zombies) can communicate telepathically.