Demon King from Today!

The Terror of Morgif, a Man-Eating Demon Sword (1x6)

Air date: May 08, 2004

Yuuri, Conrad, Yozak and Wolfram arrive on the island and have to trek all the way up a mountain. They find Morgif at the bottom of a lake of boiling water and Yuuri has to dive in and get it. He's too wimpy at first, but after overhearing a conversation between Yozak and Conrad he goes after it again on his own and overcomes his fear.