Traveler

The Travelers are a non-corporeal race of unknown origin that arrived in Theldesia during the Catastrophe (which they call the Eclipse), just like the Adventurers. This race is split into two factions: Fool and Genius.

It is important to note that "Fool" and "Genius" are the way their names are supposed to be pronounced and were written as ruby characters. Their actual kanji mean "Inspector" and "Gatherer," respectively.

Overview
The members of this race did not have physical bodies to begin with, so they had to take bodies that already existed in Theldesia (either accounts that were inactive at the time of the Catastrophe or the bodies of monsters).

The Genius intend on focusing their efforts on destruction and chaos while gathering Empathium (as their name suggests), while the Fools seem more interested in observing the other players as well as the physical sensations and experiences that Elder Tale has brought to them (likewise, as their name suggests).

They have a better understanding of the Catastrophe than the Adventures, however Roe2 admits they don't have a solution for it.

Route 43 arc
Tohya's Party, while traveling in the Sakawa Region, encounters a group of People of the Land facing a horde of Ogres when they hear a voice through the trees warning them of more higher level ogres being on the way. As the group is fighting the monsters, Roe2 appears out of the forest to join them in battle and summons a Princess Wraith to aid them in battle. She also formally introduces herself to the group and reveals that she is a vampire who is also travelling to the south in order to change her subclass, complaining that the person who chose it for her gave her a rather cumbersome one

She watch's the invasion of Wyverns in the city of Saphir and the Odyssea Knights' repeated suicide tactics, which she believes to be part of the Genius plans, since it creates something called "Empathium." Minori asks who Roe2 really is. She answer she is a Traveler and gives a long explanation beyond anyones comprehension. In the end she joins the battle against the Wyverns.

After the battle she hands Minori a letter addressed to Shiroe.

Kanami, Go East arc
In China, Kanami's Party hears reports that the Lelang Wolf Cavalry was wiped out by undying monsters. Upon hearing this, Kanami decides to go face down these monsters, with Elias Hackblade and Coppelia following her. Although Leonardo initially hesitates, he agrees to go after talking with K.R.. The party is successful in killing the two Genius monsters they face, although K.R. is killed and sent back to Yamato in the process.

Later it's revealed that K.R. have joined Plant Hwyaden in order to gather more information about these monsters. From his research, the Genius were moving around the server and walking around, unseen and unknown. One is in Nakasu, while two are in Akihabara.

Homesteading the Noosphere arc
Shiroe reads Roe2's letter, that was written while Tohya's Party was in Sapphir. The preface explains that she is a Traveler, a race of mental bodies that were brought to the world of Theldesia because of the Catastrophe, which they called the Eclipse (its kanji means "pact"). She continues to explain that her race has two factions the Fools and the Genius. While the Travelers had an explanation for the Catastrophe, it wasn't a solid principle and they had no solutions as to how to return to their own world.

Other Media
In the Log Horizon TRPG the adventures face and kill the Genius Monster called Sislau.

Fools Faction

 * Roe2

Genius Faction

 * Heiglot
 * Mascarvin
 * Mizkun
 * Papus
 * Rasphuia
 * Sachluph
 * Sislau