Aka: So Aqua who can only get his d*ck hard with his now mother (look at Akane imitating his mother), who better than getting with her daughter, who just happens to be his now sister, who just happens to be the re-incarnation of an underage girl who he took care for and treated of cancer.
Aka fans: Masterful gambit, sir.
Even if Aqua turns her down, the fact this "I'll marry you when you become 16" plot is even part of the script is stupid, doesn't bring anything to the main story and a waste of time, the writing has been going downhill for a while.