He has the appearance of a gold and white dog.
In legends, Seasarmon was said to be the guardian of the island, a talking dog.
Minami's father Takehito created Seasarmon as the original V Pet after her puppy Mei drowned in a storm. Minami felt that the V Pet could never replace Mei. However this V Pet contained the vaccine program, and when Minami was threatened by Divermon, the V Pet jumped out of the computer as Seasarmon and destroyed Divermon.
Later, Minami was captured by Mantaraymon, who whipped Guilmon and Seasarmon with his tail. Seasarmon traveled with Takato, Guilmon, and Kai to find Minami, but was pulled into the water by Depthmon. Seasarmon destroyed him and entered Mephistomon's base with the others.
Mephistomon's right hand man, Baromon, had a laser turret shoot at Seasarmon, who ran on the wall to avoid it. He later fought Baromon alongside Growlmon, distracting him so Growlmon could destroy him. Then Mephistomon revealed himself and punched Seasarmon, mortally wounding him. He dedigivolved to Labramon and was later sent flying into Mephistomon's digital world. When Minami called him "Mei", this enabled him to release the vaccine program, destroying Mephistomon's minions and virus. However, Labramon succumbed to his injuries, and was destroyed.
Seasarmon can charge his paws with gold energy and use them to damage or destroy his enemies.
- His name is derived from the mythological Siisaa.
- He looks similar in appearance to Caturamon. Both dogs are voiced by Tom Wyner.
- When he runs on the wall avoiding the laser turret, this is similar to the scene in the Dragonball Z movie The World's Strongest, where Krillin is running on the wall avoiding Dr. Kochin's machine gun. This scene is shown in the Dragonball Z opening.