To Heart: Remember My Memories2004
Drama
Romance
School
Sci-Fi
Harem
Slice of Life
This anime has a potential prequel!
Time flies by; Hiroyuki and Akari are 12th-graders now. Both of them and their friends have grown up gradually in someway, physically or mentally, but one of their best friends is missing: the lifelike android Multi. To their surprise, Multi is brought to their campus again without notice, yet she is no longer the same Multi they have known. (Source: ANN)