Claim: The episode 1 of Gate Keepers 21, a six-part sequel OVA series to the Gate Keepers animated TV series and has a darker and more serious plot than its predecessor, had an original airdate of April 24, 2002.
Evidence: Gate Keepers 21 (ゲートキーパーズ21, Gēto Kīpāzu Nijūichi) is a six-part sequel OVA series to the Gate Keepers animated TV series and has a darker and more serious plot than its predecessor. "Encounter"
Transcription: "Deai" (Japanese: 出会い) April 24, 2002 (2002-04-24)