Murder at Mount Fuji by Shizuko Natsuki

When American student Jane Prescott is invited to spend the holidays with her classmate Chiyo, she jumps at the chance to see in the new year at a luxurious mansion at the foot of Mount Fuji. Chiyo belongs to one of Japan's wealthiest families, the heiress to a pharmaceutical empire headed up by Yohei 'Grandpa' Wada. With the whole Wada family gathered and snow falling outside, the festivities are in full swing. That is, until Chiyo bursts into the room - covered in blood, holding a knife, and screaming that she has stabbed her grandfather to death.