The earthquakes will test the business continuity plans that Toyota and its Japanese peers drafted after natural disasters hit the nation’s east coast five years ago and disrupted operations for months. The stakes are high for Toyota because it relies on domestic manufacturing more than its peers. The company and its affiliates made more than 4 million vehicles in Japan last year, 40% of their worldwide output. Nissan Motor Co. and Honda Motor Co.’s shares of auto production from Japan were 17% and 16%.