Umi no Triton (2000)

Screened at the Glass no Chikyuu wo Sukue: Oyako Forum - Tezuka Osamu kara 21-seiki no Kimitachi e event at Himeji Welcome 21. In addition to the familiar characters from the original work, original characters Marine and the event's mascots Kirara and Mirara also make appearances. (Source: Official site, translated)