http://www.caramel-box.com/index2.html
Main site : http://otbk2.com/
Full name : Otome wa oneesama (boku) ni koishiteru - Futari no elder
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To tell the truth, I was very happy when I heard this. Not only that Otoboku was the very first anime that got me into traps, but Mizuho-chan (aka Mizuho-oneesama) is also one of the best traps ever :D Okay, moving on the main topic, according to Caramel Box, the game will most likely be released in this year. If I'm not wrong, there will be a new protagonist in this game. Let's wait and see what this game will be. Cheers :D