X-Less' Hero Costume consisted of a blue bodysuit with a light upper half and a darker bottom half. His sleeves were decorated by a dark blue section with three yellow stripes and larger dark blue stripe wrapped around his head and over his right eye. He also wore a red cape.
Sometime before the Paranormal Liberation War Arc, he added a pale lens over his right eye, presumably designed to aid his Quirk.
X-Less was a cautious individual as he opted to destroy an unknown machine inside the villain's lair before carrying on with his mission.
X-Less is one of the Heroes who assaulted Jaku General Hospital, coming into conflict with several High-End Nomu. Alongside Present Mic, however, he managed to get to the room where Tomura Shigaraki was being operated on, finding him in a death-like state after Present Mic interrupted the procedure.
Present Mic tasks X-Less with disposing of Tomura while he takes care of Kyudai Garaki. Before doing so, X-Less notices a strange machine still working because the nearby tubes protected it from any damage. Although X-Less doesn't know its purpose, he decides to take no chances and destroys it.
Unfortunately, a destroyed wire falls into the puddle of Tomura Shigaraki's sustaining fluid, which electrifies it and causes Shigaraki to recover from his near-death state and awaken. X-Less is stunned as Tomura proclaims his discomfort, stating that he is cold. Shigaraki then kills him, taking the deceased hero's cape for himself. However, it turns out that X-Less' efforts were not in vain as the machine was dedicated to producing the Quirk-Destroying Drugs. With its destruction, most of the drugs are wasted.