In the space year 6216 (1422 in the original Arcade version), the Fantasy Zone was cast in panic at the collapse of the interplanetary monetary system. The Space Guild reveals the plans of the planet Menon, whose forces are stealing the other planets' currencies to fund a huge fortress in the Fantasy Zone. Opa-Opa is sent to the Menon system after they stole supplies from other systems. It is revealed that Opa-Opa's father is the leader of Menon.
Fantasy Zone II: The Tears of Opa-OpaEdit
Fantasy Zone II: The Tears of Opa- Opa takes place 10 years after Fantasy Zone. Opa-Opa is once again sent to defeat the Menons. As it turns out, the mastermind behind the Menons is Opa-Opa's bad self. Due to the emotional stress caused by the war he fought 10 years ago, he had split into two beings; one of them good and the other bad. Only O-Papa was aware of this fact and thus became leader of the Menons because of his bond with his son.
Opa-Opa is 38 cm high (14.9 in), 40 cm wide (15.7 in), and 52 cm (20.5 in) long . Its feathery white wings are 19 cm (7.5 in) each and it weighs 16.8 kg (37 lb).  It has an opaque cyan screen, is red in the back and green on the bottom. Coming out from the bottom are two skinny yellow legs with large feet.
Appearances in Other GamesEdit
- Opa-Opa appears in a secret Fantasy Zone mini-game , in Arnold Palmer Tournament Golf, for the SEGA Genesis.
- Opa Opa is a playable character in Sonic and Sega & Sonic All Stars Racing. It can be unlocked for 32,000 SEGA miles on the ds ye costs 100,00 sega miles.
- Opa-Opa is an extreme gear available in Sonic Riders
- Bio: "Opa-Opa is a sentient spacecraft, battling to stop the planet Menon from stealing the other planets’ currency to build a huge fortress. In winning this battle, Opa-Opa hopes to restore peace to the Fantasy Zone. Opa-Opa can hover and fly using its wings or sprout feet to walk on the ground."
- Opa-Opa appears in Samba De Amigo as a song, "Opa-Opa!".
- Opa-Opa appears as a toy in the capsule machines in Shenmue.
- Opa-Opa appears as a cameo appearance in the Sega Master System title Zillion.
- Opa-Opa appears as a Mag in Phantasy Star Online.
- Opa-Opa appears as a small decoration in Hatsune Miku: Project Mirai DX
- Opa-Opa cameos in a boss fight in the game Alien Syndrome.