English Name: Marcus Damon
Japanese Name: Daimon Masaru
School: Otari Municipal Junior High (8th Grade according to dub)
Birthday: 2nd April
Blood Group: B
Partner: Agumon > Geo Greymon > Rise Greymon > Shine Greymon > Shine Greymon Ruin Mode > Shine Greymon Burst Mode, Agumon "Burst Mode"
Masaru Daimon is the typical "tough" guy. He has a rough exterior, but inside he truly wants to help people. Because of this, he has self-proclaimed himself to the #1 Japanese street fighter. Even with the encounter of his partner Digimon, Agumon, he couldn't help but to have a brawl.
With Digimon being new to Masaru, so was the new headquarters of DATS. There, he joins the as a member, after having defeated his first Digimon, Cockatrimon, with Agumon. They were surprised he could make Agumon evolve, but it only shows to prove that a bond was already forming. Masaru lives with his mother, Sayuri, and his little sister, Chika. Ever since his father disappeared, he has become the man of the family, always taking care of his mom and sister. Even with Agumon and with his new duties at DATS, he somehow manages to still take on that role.
Even when Masaru is helping Yoshino and Touma on missions, his mouth still yaps on over things that's out of his control. Breaking the DATS' computers isn't uncommon, but he makes up for it out in the field, when he and Agumon take on larger, and more powerful Digimon. When he gets a rival of Kouki he slips back to his older ways thus confilict between him and Touma has begun to notice. It boils over when Touma goes to Kurata when his father sent some of his own men to take Touma Home. Touma ends up fighting with Masaru with disaterous effects as Masaru's anger causes Shine Greymon to wrongly Burst Mode into an evil beast and eventually back to a Digitama.
When Masaru realises Touma's intentions he ends up making Agumon evolve to the correct Burst Mode. He finds his father is still alive but as Yggdrasil. He has to fight Yggdrasil and in the final battle Masaru fights with Agumon who has Burst Power in order to defeat Yggdrasil. He goes to the Digital World to stay with Agumon.