Hamuko's nature as Minato's Shadow. It's confirmed that she works on Video Game/Persona4 Persona 4 mechanics. How was she first introduced? As someone very different from what Minato was initially like but also similar to how he eventually turned out.
Remember how Minato keeps taunting Hamuko about being a shotacon? And at one point she says she's tired of people always saying those things, and Minato is like "So this has happened before?" Remember the visions? And how both Hamuko and Minato have gone through loops a billion times? Hamuko's probably heard him tease her that many times that she's acts like this by TFT.
After Hamuko talking about her thoughts of suicide and how she would go to the bridge and think about jumping, makes you think about all the times she wasn't on screen.