Konjiki no Gash Bell!!: Unlisted Demon 101

During the Summer holidays, Gash and gang decide to head for Fuji Mountain for a picnic gathering. There, they encounter a girl with a white magical book. Her name is Kotoha and her book has a message saying that Gash's mother is located a cave in the forest. However, when they eventually found the cave, there was already a blond-haired youth by the name of Wiseman. (myanimelist.net)