Mild pedophilia. probably yes. Grooming, I don't think so (it was the little girl who started into motion their love affair and the Onee was the one holding back). Strong Pedophilia with intended rape, I don't think so. No. So far I have never read in psych journals about rapists pedophiles wanting their victims to turn 18 or become mature enough before they could have romantic/sexual intercourse with them. I mean, this Itou Hachi story is completely different from the pedophilia with grooming and rape which we should all rightfully abhor.
Reading Itou Hachi's recent works with almost the same topic, it gives me the impression that the romantic aspect essentially is not about the lolicon or the age gap thing. I think it's the idea of holding back and for how long lovers can hold back that kicks off the romance. I might be wrong but for now, that's what it seems to me.