[Help] can someone tell me the name

So our mc transports inside a novel or game (I don't remember) he is the son of an noble and he has an step sister who has light blue hair. She hates him at first (don't remember why) she is apparently one of the strongest characters in the future so mc reconciles with her somehow to break flag but he raised the step sis flag instead. He then has a fiancee with blond twin tails who is an sadist. She also falls for him after going back in time (oh right mc can go back to a certain point in time due to his awakening or something I don't remember how the power system works here) and he helps her awaken her power that's all I remember it was in bilibili.