[3] In early 2018, Keonhee and Hwanwoong, with the addition of Ravn and Seoho, were introduced as pre-debut team RBW Boyz, and Leedo and Xion were added in March 2018.

[6] The group's debut EP Light Us was released on January 9, with "Valkyrie" serving as its lead single.

The tour made stops in six cities: New York, Chicago, Atlanta, Dallas, Minneapolis, and Los Angeles.

[16][17] "808" debuted at number 1 on the Oricon Daily Single Chart with 3,662 copies sold on the first day of release.

[18][19] On January 10, 2020, Oneus held a fan-meeting in honor of their one-year anniversary, called Our Moment, at Yes 24 Live Hall in Seoul.

[25][26] On March 20, it was announced that the group would join Mnet's reality television competition Road to Kingdom.

[27] For the show's finale on June 12, Oneus released their song "Come Back Home" and finished in fourth place overall.

[30] On January 19, the group released their first studio album Devil, which consisted of eleven tracks, including the lead single "No Diggity".

[34] On November 9, the group released their sixth EP Blood Moon, with the lead single "Luna".

[38] In April, Oneus announced two stops to continue their Blood Moon tour, holding their third and fourth Japanese concerts with shows in Chiba and Osaka.

[44] On October 17, due to reports of inappropriate behavior, RBW announced the temporary suspension of Ravn's activities until a fact check could be completed.

[48] The EP contains five tracks, including the lead single "Erase Me," and it also marked their first release as a five-member group.