Free manipulation of all fluids is legitimately one of the most overpowered abilities fathomable, And that's why in almost all cases writers have to nerf it by saying "oh no it can't manipulate water that's part of other creatures". Because if they don't, you can just immediately desiccate...
Nanami is growing into such a fine person, and it's nice to see the role reversal for once.
That said, the "overworked parent goes to the hospital for anemia and is then all better and it's not an issue in the end" is so overplayed.
Honestly I hope there isn't some dumb deus ex machina that has him pull the win out of his ass. The loss should be a moment of learning.
"It is possible to commit no mistakes and still lose. That is not weakness, that is life."