Desire To My Beloved Stepsister

Lucy had never met with Kyle— her stepbrother for seven years, and when Kyle returned due to the death of Lucy's biological mother, the mysterious Kyle showed another side Lucy never knew. 
"I love you." 
Kyle forcibly says his love for Lucy after he gets caught masturbating while calling Lucy's name over and over again.
This honest remark from Kyle made Lucy shaken. 
They are brother and sister ... They can't have a special relationship, right?
Lucy was about to distance herself from Kyle, but Kyle became more aggressive to get Lucy's heart.
Can Lucy melt on Kyle's action who is her stepbrother? Lucy was completely at a loss to face Kyle who was full of charm.