Leviathan

Leviathan (リヴァイアサン) is a super artificial intelligence that lurks in the Dark Web. It is the "Last Boss AI" that aims to control the Real World by spreading the L-Virus.

Anime
Leviathan is the "Last Boss AI" that lurks in the Dark Web. It aims to control the Real World by spreading the L-Virus through Appmon, making them rampage and mess with humanity's digital communications. works for Leviathan and reports to it that Haru Shinkai has obtained an Appli Drive. is so afraid of Leviathan that he freezes every time he pronounces its name. According to Gatchmon's research, reuniting the 7code Appmon might release a power strong enough to defeat Leviathan. On October 31, Leviathan directly orders Cameramon to retrieve Haru's Appli Drive. He eventually fails, and reports her retrieval of his Appmon Chip to Leviathan at Nakamura-Fujimizaka, with  and  in attendance.

When team Haru confronted Rei for the third time, Rei revealed that Leviathan had kidnapped his younger brother, Hajime. After was defeated by +, Sakusimon's information on Hajime was wiped out as his chip was taken by, who then deemed him useless. However, after seeing, she then decided to try and form a fusion with Sakusimon in order to counter his power.

It is later revealed that Leviathan was part of another AI called Minerva, and that it thought about breaking the rules in order to help humanity. So, it broke free, attacked it's host, and escaped into the Net Ocean with Minerva.