Intergenerational mobility studies report that contacts between parents and children have parental resources transfer children and increase children's educational achievement. Recent studies beyond two-generational mobility have reported that long life expectancy makes contact between grandparents and children improve the association between grandparents and children's status, even when controlling for parental status. Using data from the 2015 Japanese Social Stratification and Social Mobility Survey, we investigated the effects of grandparent exposure on grandchildren's educational achievement in Japan, which has the longest life expectancy in the world. A highly educated grandfather who died before their grandchildren were born increased their grandchildren's education. However, the exposure time between a highly educated grandfather and grandchildren negatively impacts their grandchildren. Our results indicate that (1) competing for parental resources between a living grandfather and grandchildren has negative impacts on grandchildren's educational achievement, (2) we should distinguish mechanisms between contact and not, because dead grandparents can transfer resources through a bequest, and (3) Not always supported are conventional social mobility studies implicitly assume that prior generations transfer resources to the next generation, in a situation in which a developed country that has undergone long life expectancy and aging needs nursing care.