Leichter, known as Daimon Kogoro in the Japanese version, is former assistant of Gozaburo Kaiba and later Seto Kaiba, as well as a member of the Big Five.

As Gozaburo's assistant, Leichter was originally next in line to run KaibaCorp until Kaiba became president instead. Kaiba states that Daimon could have never run the company successfully due to his insufficient strategical ability and lack of own personal ideas.