LE SSERAFIM has been at the center of popular online discourse in South Korea recently. LE SSERAFIM | @le_sserafim/Twitter On May 15, a netizen posted multiple pictures taken at a LE SSERAFIM concert, pointing out that a large section of the audience consisted of middle-aged men or Ahjussis. | Nate Pann | Nate Pann The…