Back in Time [WMatsui fanfic]

Year 2050. Rena Matsui, a 26-year-old charismatic young woman, is at the head of one of the most successful companies in Japan. One of her wildest dreams is to build a time machine to go back in time, a technical exploit never achieved by anyone before. To fulfill her wish she gathers a team composed of the best scientists in the country, including her best friend Akane Takayanagi. When the project reaches an impasse, she recruits a 24-year-old girl praised for her talents, the very charming Jurina.

Trailer video: https://youtu.be/pGrgW6pinjw
(the video contains a heavy spoiler for chapter 12 & onwards, so beware if you haven't reached that stage yet!)