Zatch Bell!

The Invisible Hunter (1x39)

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Zatch loses at a lottery to win a yellowtail fish and a man decides to take pity on Zatch and gives him his tickets to an onsen. At the onsen, Kiyo finds a note in his room revealing the location of a secret onsen and an all you can eat yellow tail buffet. Upon arriving at the location, Kiyo realizes that it's a trap and they attacked by a Mamodo named Baransha and her human partner Garza. Kiyo and Zatch are at a disadvantage since Baransha can attack from afar and become invisible. As the battle drags on, Kiyo uses ginkgo nuts' strong scent in order to track down the invisible Baransha. Kiyo and Zatch gain the upper hand with "Bao Zakeruga" but Garza and Baransha manage to escape by jumping into the river.