《烏龜報恩》是日本古代的童話故事，描述浦島太郎在海邊拯救一隻海龜，海龜為表達謝意，帶浦島太郎前往龍宮，並受到公主乙姬的熱情招待。經過幾天的旅行後，浦島太郎準備回家，臨走前被贈予一個玉手箱，乙姬交待千萬不能打開。返回陸地後，發現地上已經過了數百年光景，驚慌失措的浦島太郎，情急之下打開玉手箱，卻瞬間變成近百歲的老翁。

1988年推出的《烏龜報恩》，故事描述在未來的世界裡，龍宮的乙姬18世被壞人擄走，浦島太郎的後代浦島健，決定與海龜一同併肩作戰，誓言與入侵龍宮的惡獸軍團對抗，救出被挾持的公主。在海外版的故事情節中，背景設定在2777年的Xexyz國度。主角阿波羅需要挑戰已經佔領五個島國的Goruza。

總共有11個舞台，分別為1.遺跡島:沿路的房間內有藏寶物，必須取得星星鑰匙，才能到機械城，最後用章魚球攻擊boss的額頭就可輕鬆擊敗，見到海苔公主 3.森林島: 只有提升水母球到Level2，才能將煩人的蜘蛛及蜜蜂摧毀，看到boss後就用章魚球秒準眼睛攻擊，就可看到綠藻公主 5.玻璃島:小心掉入洞穴，利用海蛇球來對付寄居蟹機械獸，迎來珊瑚公主 7.湖島:敵方攻擊會更強，設法到補血的地方，就可持續前進，看到boss就攻擊頭部或尾巴即可，擊敗後會看到蠑螺公主 9.火山島:加快移動速度前進，記得取得珍珠雷射的武器，對付這關的boss可以使用，或是用海蛇球移動到右下方後持續攻擊boss，之後就可看到真珠公主 12.哥魯查城: 在12-3關，通往最後boss的房間都是隱藏，需要打敗巨大的機器人，入口就會出現。對付最終boss，用干貝鏡的效果最好，也可考慮海蛇球或珍珠雷射。全破後就可解救乙姬18世，結局會跟日本童話故事類似，出現一個寶箱，可以選擇打開、不打開、丟棄，總共有三種不同結局。

與各關BOSS對戰的密碼:“BBAI3 57912”。進入射擊畫面的密碼:A2A4A 6A8AO”。 最後關卡的PW:"E3D3D 3D3DF”。"5C2B5C8A1E"。

"Kame no Ongaeshi -Urashima Densetsu" is an ancient Japanese fairy tale that tells the story of Urashima Tarō, who saves a turtle by the seaside. In gratitude, the turtle brings Urashima Tarō to the Dragon Palace, where he is warmly welcomed by Princess Otohime. After a few days of travel, Urashima Tarō prepares to return home, and before he leaves, he is given a jeweled box by Otohime with strict instructions not to open it. Upon returning to the land, he finds that hundreds of years have passed. In a state of shock, Urashima Tarō opens the jeweled box and instantly transforms into an old man nearing a hundred years old.

In 1988, a new version of " Xexyz "(Kame no Ongaeshi -Urashima Densetsu) was released. This story is set in a futuristic world where Princess Otohime XVIII of the Dragon Palace is kidnapped by villains. The descendant of Urashima Tarō, named Urashima Ken, decides to join forces with the turtle to fight against the invading evil beast army and rescue the captured princess. In the NES version, the story is set in the land of Xexyz in the year 2777. The protagonist, Apollo, must challenge Goruza, who has already conquered five island nations.

The game comprises 11 stages:

Ruins Island: Hidden treasures are in the rooms along the way. You must obtain the star key to reach the mechanical city. To defeat the boss, attack its forehead with the octopus ball to see the Nori Princess.

Forest Island: Upgrade the jellyfish ball to Level 2 to destroy annoying spiders and bees. Aim the octopus ball at the boss's eyes to see the Algae Princess.

Glass Island: Avoid falling into holes and use the sea serpent ball to defeat hermit crab machines. You will meet the Coral Princess.

Lake Island: Enemy attacks are stronger here. Find places to heal and continue moving forward. Attack the boss's head or tail to see the Conch Princess.

Volcano Island: Increase movement speed and obtain the pearl laser weapon. Use it or the sea serpent ball to attack the boss from the lower right side. You will meet the Pearl Princess.

Golucha Castle: In stage 12-3, the path to the final boss's room is hidden. Defeat the giant robot to reveal the entrance. The best weapon against the final boss is the scallop mirror, but the sea serpent ball or pearl laser are also effective. After defeating the boss, you rescue Otohime XVIII. The ending mirrors the Japanese fairy tale, presenting a treasure box with three choices: open, not open, or discard, leading to three different endings.

Passwords for fighting each stage's boss:"BBAI3 57912"

Entering the shooting stage password: "A2A4A 6A8AO"

Final stage password: "E3D3D 3D3DF""5C2B5C8A1E"