Tower of the Future(1995)

Mirai no Utena appears to be the story of a perfectly normal boy, Matsuyuki Takeru. He deals with his mother's death and the knowledge that he has a half-sister he's never met; falls in love; and muddles his way through entrance exams. But there's also a mysterious child, Zen, who keeps appearing. As Takeru gets to know Zen better, he is drawn into a centuries-old rivalry between two families, and his real life becomes more and more like the RPGs he loves, until he is literally fighting for his life.

(Source: Anime News Network)