These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Sister Princess
Designated Villain: Akio doesn't really do much at all, let alone anything villainous, but he's treated as such after the Wham Episode. Of course, at the end he shows up to stay on the Island and everything's hunky-dory.
Ear Worm: "Love Destiny," the OP theme song, is this to many.
Ho Yay: Between Wataru's lighting up upon receiving Akio's e-mail, and Akio's 'convincing' Wataru to return with him, not to mention his reaction when Wataru decides to stay on the Island...
Tastes Like Diabetes: When this series isn't getting creepy with the incestuous overtones, it feel like your veins are being repeatedly jabbed with a needle full of liquid sugar.