Kuroko Tachisuya or 'Chisu' , the twin sister of Kuroko Tetsuya spent her life in the hospital for 10 years because of her Rheumatic heart disease which the doctors discovered when she was still in her mother's womb. She was diagnosed when she was 6. After 10 years of being 'imprisoned' in the hospital, the doctors said that she was one step away in recovering from her disease that's why her family decided to enroll her on her twin brother's school to at least live like a normal teen like her brother. She felt like an alien being transferred to earth to interact with humans. She never really interact with other humans before except her family. She studied on line, had few friends on line. Her life is the internet. Imagine her being with other human beings. Can she live her life the fullest with the 'Real world'?