Full immersion

When Christian signed up for a semester abroad, he hadn't expected anything like this! When he first touched down in Japan, he was greeted at the airport by a friendly family--a mom, a dad, and their daughter--who brought him immediately to the school. The officials explains to Christian that the exchange program he had agreed to was a true full immersion experience, and that this might not be what he expected. Christian nodded hesitantly. The next thing he knew, the school nurse injected him with a needle, and he passed out. He awoke back at the family's home, but he was shocked when he discovered he was in the daughter's body! They had done something to switch his body with hers! He had no idea this was what they meant when they said "full immersion!"