So, let's do a little math. Munakata must have been at least 22 (minimum age for grad school) when he met Machi. So assuming Machi's daughter was in her mid-20s when she had her daughter, and said daughter is in her mid-20s now, that makes Munakata at least 70 years old. How old is Imibe again? Wasn't she in her late 30s when she was introduced? There's a 30-year gap?