トゥハート ~remember my memories~

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)