Risa no Yousei Densetsu

Sinopsis en inglés

You take the role of a boy visiting a concert of popular Japanese idol, singer and actress Risa Tachibana. During the concert the sky darkens, lightning strikes and he and Risa get mysteriously transported into a fairy land, which is threatened by an evil witch and her minions. So starts their adventure to overcome the evil witch and find a way back to their own world.