Tomoyoshi Tayama

Tayama is adventurous and willing to enter dangerous underwater environments in pursuit of valuable discoveries. Like his companions, he approaches Koumi Island as a professional treasure seeker rather than an ordinary tourist.

His limited screen time means little of his personal background is established. His characterization is primarily defined by his occupation, his association with the other treasure hunters, and the danger surrounding their search.

Tayama has no supernatural abilities. As a professional treasure hunter, he is physically capable and experienced with diving and underwater exploration.

He uses specialized diving equipment while investigating submerged sites around Koumi Island and is willing to enter waters where environmental hazards make exploration dangerous.

Tayama arrives on Koumi Island with Matsumoto and Izuyama while Kogoro's group is vacationing there. Their presence attracts Conan's attention because they are clearly searching for something more substantial than the island's tourist attractions.

During an underwater expedition, sharks suddenly attack Tayama, fatally injuring him. Investigation of his equipment reveals that blood had been placed in his buoyancy compensator, deliberately attracting the sharks rather than making the incident a simple diving accident.

The attack becomes one of the major clues proving that someone else is manipulating the treasure hunt. Conan eventually traces the scheme to Jouji Iwanaga, who wanted to use the professional hunters' efforts while clearing obstacles from his own path to the treasure.

Mitsushi Matsumoto is one of Tayama's fellow professional treasure hunters on Koumi Island.

Taro Izuyama is the other member of Tayama's treasure-hunting group.

Jouji Iwanaga interacts with the treasure hunters through the island's tourism operation. Iwanaga secretly manipulates their expedition and is responsible for creating the conditions that lead to Tayama's shark attack.

Conan Edogawa investigates the circumstances surrounding Tayama's attack and realizes that the apparent diving accident was deliberately engineered.