Koikimo (Manga)

Synopsis

Once you fall for someone, you can't stop the love. A strange encounter spurs the meeting of Ryō Amakusa, a high spec businessman who's loose with women, and his high school sister's best friend, Ichika Arima. From there he falls madly in love. On the one hand, he approaches her with almost too straight-forward methods, while she responds simply disgusted, insulting him without hesitation... and he takes it as her way of showing love.