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Isaiah (Japanese: イザキ Izaki) is a character of the day who appeared in Clamperl of Wisdom.
He runs his own research laboratory and museum on Maisie Island, which hosts several Clamperl in a pool enclosure. While diving off the coast of the island he discovered a blue pearl, similar to those made by Clamperl. He wanted to do some experiments on it so he could discover more about the rare find. The blue pearl proved a tempting steal for Team Rocket, though Spoink bounced off with the pearl after it lost its own pink pearl.
Along with Ash, his friends, and Spoink, Isaiah found the pearl inside of a wild Clamperl, which believed it was its own. Team Rocket intervened and stole the Clamperl, however, the group didn't give up, and were able to rescue the Pokémon.
Spoink was able to convince the Clamperl to give the blue pearl back to Isaiah. Now with his pearl safely returned, Isaiah began his research on it while the group continued their adventures in Hoenn.