Jouji Iwanaga

Iwanaga presents himself as nervous, bumbling, and eager to please visitors. He helps arrange accommodations when Kogoro's group encounters problems with its hotel reservation and encourages the visitors to participate in the island's tourist activities.

He is knowledgeable about the local legends surrounding Anne Bonny, Mary Read, and the treasure supposedly hidden around Koumi Island. His enthusiasm for the treasure hunt initially appears consistent with his work promoting tourism.

The awkward persona conceals a greedy and calculating side. Iwanaga is prepared to manipulate other treasure hunters, endanger people, and exploit their discoveries in order to reach the legendary treasure himself.

Iwanaga has no extraordinary abilities. His primary advantages are his detailed knowledge of Koumi Island, its tourism infrastructure, and the local treasure legend.

He proves adept at deception, successfully maintaining an innocuous public persona while secretly interfering with the treasure hunters' expedition. He also understands enough about their routes and equipment to manipulate events without immediately attracting suspicion.

Iwanaga greets Kogoro's party after their arrival on Koumi Island and helps arrange their stay at Kazuo Mima's inn. He also introduces the visitors to activities centered on the island's famous pirate treasure.

The treasure hunt eventually becomes dangerous when professional treasure hunters pursue the same legend and Ran Mouri and Sonoko Suzuki are drawn into their expedition.

Conan ultimately exposes Iwanaga as another party secretly pursuing the treasure. He had manipulated events from behind the scenes, including using blood to attract sharks to Tomoyoshi Tayama and later following the surviving treasure hunters to the hidden site. His plan collapses after Conan uncovers his involvement.

Kogorou Mouri and his companions meet Iwanaga through his work for Koumi Island's tourism office.

Conan Edogawa becomes increasingly suspicious of Iwanaga as the treasure mystery develops. Conan eventually identifies Iwanaga's concealed role in the dangerous events surrounding the treasure hunt.

Kazuo Mima owns the inn where Iwanaga arranges accommodations for the visiting group.

Tomoyoshi Tayama is one of the treasure hunters active on the island. Iwanaga's scheme contributes directly to the shark attack that kills Tayama.

Mitsushi Matsumoto is another treasure hunter whose search Iwanaga secretly exploits in his own pursuit of the hidden treasure.