My Future Self Will Be Awesome

My name is Jiang Liu. One day I suddenly received a WeChat message from my sister who is terminally ill and has been mysteriously missing for two years. She said that she was in the future world now, and it was me from the future who took her there and cured her terminal illness. Moreover, she also said that I will be super powerful in the future! By the way, she also taught me a technique that is said to be very awesome...