Shin Kyuk-ho, the founder of one of South Korea’s biggest and best-known conglomerates, has sought to crown his rags-to-riches success story by building the country’s tallest skyscraper. In addition to the Lotte World Tower rising on the banks of the Han river, the 92-year-old is also likely to be remembered for his failure to map out a clear succession plan that has triggered a feud so intense that it has riveted a nation accustomed to warring corporate families.