Poor succu-chan doesn't realize just how far behind she is in this race. I trust the author to give her some happiness, they've already set up some cute potential for medusa+invisibo so there's a good chance Ako's story will eventually go her way as well. Just not with our boy.
And I love that little subversion of expectations with the date reaction. I was expecting Ako to be jealous finding out, but her first reaction was "what a good brother!!"