Yoshitaka's parents are boomers or worse, it's very rare for a father taking custody of a child, even if he was widowed this isn't any bad deal either way. Who cares if it's not her child, they're royalty, preserving purity of a bloodline?
What's worse she doesn't realise she too has a relationship with even bigger age gap, since An is 20 and kid looks around 5 father is just about 5 years older than her, Yoshitaka is 25 and Arase 17 they're a whooping 8 years apart.
There's seriously wrong with Miyuki and Seiji "chemistry " in their relationship and unfortunately Yoshitaka inherited those traits.
Also, yay, Mako is back, unfortunately.