Travel Through Time and Become a Girl, Merge with Heather at the Beginning

Single female protagonist, city, campus, system, Lin Yu was watching Hai Seyin's PV at Shanghai University, and he liked it very much. It later became XP. The good news is that there is a system for time travel, but the bad news is that she turned into a girl, and it was the reason why his favorite Heiseyin traveled through time and was knocked away on the way back to school.