MagusTale Eternity: Seikaiju to Koisuru Mahou Tsukai (2009)

Am I dreaming? I just came to the island to inform Koyuki, my younger sister, who is a student of a boarding high school located on the island, that our father is missing. I was perceived as an intruder, and attacked with magic. I'm now damaged so badly.... Without Koyuki, I'd have surely lost my life. Anyway, I know the reason why this school is isolated from the outside world. This school is actually established to train magicians. Like this, my new life on the island starts....