In the unique VR game 'Monsters Evolve,' players don't hunt or command monsters; they become monsters. This game gained unexpected popularity, and its online version, 'Monsters Evolve Online,' has just been released as a VRMMORPG. Keigo Yoshizaki, a fan of the offline version, immediately buys and plays the online version. However, many specifications have changed from the offline to the online version, most notably that the initial race is randomly determined. His randomly assigned race is 'Moss,' and he must figure out how to play the game. This story follows his journey using this unusual race, experimenting with various plants and animals, competing and fighting alongside three factions in a world without humans.