Ichisumi was born around 1833 A.D. in Kumamoto, Japan. Ichisumi was the daughter of a proud samurai, and constantly disappointed her father in her occupation of a geisha by never getting chosen by any wealthy men. This led to Ichisumi later suffering from an acute inferiority complex; upon the manifestation of her mutant power, she had her Yume beetles attack all of the other geisha she believed to be prettier. The beetles went through hundreds of women until they returned to her; when they did, she was unaware, or did not care, that she would mentally link with them, and the mutilation of the beetles drove her mad.
Ichisumi was watched by the eternal mutant Apocalypse and selected as his Final Horseman Pestilence in the event that all other plans of Apocalypse failed. She was first shown on the Blue Area of the Moon, fighting Deadpool from X-Force. Fantomex later played a mind trick on her, and did so again to her and the rest of the Horsemen to teleport them to the wrong place.
Dark Angel Saga
Pestilence returned with the rest of the Horsemen, now working for the new Apocalypse, Archangel; they fought the X-Force, and later Psylocke when she escaped from the Clan Akkaba headquarters. She was shown in bed with Archangel, and later Dark Beast revealed her to be pregnant with his child after the remainder of Apocalypse's team escaped from their headquarters right before its explosion.
The Apocalypse Twins
Some time later, Pestilence joined her fellow Horsemen War and Famine, and Apocalypse's son Genocide at the space station Starcore to gain the approval of the Celestials, so Genocide could take his father's place as the new Apocalypse. Before Genocide could receive the Death Seed from the Celestial Gardener, Pestilence's children appeared from the time stream, fully grown, and planned on usurping Genocide's place as the new Apocalypse. The Twins killed Pestilence's fellow Horsemen, Genocide, and the Celestial Gardener, but they spared their mother and rescued her as the Celestial's death throes destroyed the Starcore Station.
As the Twins prepared to carry out their plan to rapture mutants away from Earth, they showed Pestilence their incarnation of the Horsemen of Apocalypse, the Horsemen of Death: Daken, Grim Reaper, Banshee, and Sentry.
Ultimately, the Twins' plans failed. Pestilence's fate and whereabouts are unknown.
Insect Control: On command, she could release an infestation of near omnivorous Yume beetles stored within her own body by dislodging her jaw, spawning from her mouth in massive swarms either devouring or disfiguring her intended mark.
- Mental Connection: She was also able to mentally link with them when they returned to her as each and every individual being her colony consumed also imparted unto them; and subsequently upon their habitat/queen, much of the victims memories.