Kingyo no Fun

Synopsis:

Kingyo is my step-sister. She was the person I loved the most in this world, but I’ve hurt her. Things can never go back to normal ever again. I hate myself for being such a coward, but there’s nothing that can be done about it. [From Sound of Jewels and Sumire no Team] Kingyo is the most lovely name in the world. She was my stepsister. She had the most beautiful smile. She was a crybaby. She was so kind that I couldn't bear it and ...I crossed the line.