From London to New York, nobody wants to be a commercial landlord these days. But in the South Korean capital, owners of office towers are living the boom life.

Seoul’s office market is every landlord’s dream: More than 98% of grade-A offices are occupied, with rents surging 15% from last year. The competition for space is so fierce that when there was a floor available in Parnas Tower at the heart of the prestigious Gangnam district, a dozen domestic and international companies turned up in a tender to outbid each other.