Aritomo's earliest activities in the entertainment industry included being the official child model for Sanrio Puroland.

[5] On November 12 and 13, 2016, she participated in the Sakura Gakuin Festival 2016 held at the Maihama Amphitheater in Chiba Prefecture, and became a member of the group's sub-unit Kōbaibu (Purchasing Club).

In 2021, Aritomo was cast in a television commercial for the Nintendo Switch video game console which was broadcast across Japan.

[12] Continuing her entertainment activities under the stage name Gumi,[13] she released her first album with @onefive, titled 1518, on February 2, 2022.

[16][17] Aritomo's vocals as ChamJam were included on the album I Live For You (きみのために生きてる, Kimi no Tame ni Ikiteru), released by Pony Canyon on May 10, 2023.

[18][19] In November 2023, Aritomo began modeling for Amazon Fashion Japan, as @onefive had been selected to be its Generation Z Leader.