Koi No Himitsu Kichi ("Hidden Base for Love") by Saki Shiumi 1 Volume (Complete)
Aisu is being forced by her father to pick a fiance but she already like someone. It's short and I only started liking it near the end. I got to give credit to the mangaka for making me think that she'll end up with... Nice twist. Thanks to Ashley and Kezzlex3 for the tip.