could it be that Asami was in love with Minato's dad and maybe she is trying to get back at the mother by taking away Minato?
at least that's the vibe I am getting so far
I'm not sure if she was in love with Minato's dad, but I am definitely getting a vengeance vibe from all of this. There is some serious bad blood between Asami and Minato's mom. There may have even been bad blood between Asami and Minato's dad. I think poor Minato is going to end up being the one to pay the price.
AND
Honestly, I think it's much simpler than it really is.
Minato's father got diagnosed with a terminal disease and Minato's mother filed for divorce.
Father left the house, rented a one-man apartment and gave out guitar lessons.
Father met Asami and taught her, bonded with her. Asami met Minato and her mother through pictures and stories.
Father died. Mother came for the inheritance, met Asami and the bad blood starts. Possible reason is that Asami resents the mother for abandoning her dying husband while Mother resents Asami for taking what was suppose to be their inheritance.
No, Asami wasn't in love with Minato's dad. He was her guitar teacher and she respected him, revered him even, but she wasn't in love with him. Whether he had a thing for her or not, I can't say, since he hasn't really been a character in the story, but I doubt that as well. I think he considered her his protege.
As for Minato's mother and the divorce and what the big secret is between her and Asami, remember that the divorce happened when Minato was three years old, so if it was due to a terminal illness, it took a LONG time for the illness to run its course. That doesn't eliminate terminal illness as a possible reason for their divorce, but it makes it slightly less likely.
My guess is that he had some sort of treatable, potentially deadly, chronic illness. Japan has universal health care, with a 30%/70% payment split, but if the treatment for his disease were particularly costly, that 30% could be prohibitive for a small business owner struggling to make ends meet. I would guess the divorce had to do with that. If he was no longer in the family, he would qualify as low income and be eligible for some government aid to pay for treatment. However, it also could be that he didn't seek treatment for some reason...
For what ever reason, we know he died...
And now we know that the last time Asami saw Minato's mother was at the reading of her father's will. That is obviously the source of the mother's anger. Asami was obviously named in the will as the heir to the majority of Minato's father's assets, with the possible exception of that CD of music?
As for the song, I have to wonder who actually WROTE it. I'm wondering if that was either written by Asami when she was a teenager and played by Minato's father on the CD or if it was co-written by Asami and Minato's father. It is obvious that Asami feels the right to use it as her own, but it is also fairly clear that Minato currently doesn't quite agree...