The character referred to as Perma in some write-ups is known in the series as Perm, a nickname derived from the word permanent and a reference to his permed hairstyle. His real name is Kousuke. He is one of Ataru Moroboshi's friends and classmates at Tomobiki High School, and he serves as a member of Lum's Stormtroopers, the self-appointed fan club devoted to the alien girl Lum, a group sometimes translated as the Lum Imperial Guard. He is a tall, thin young man with brown hair and dark eyes, and his hairstyle is his most distinguishing feature.

In terms of background, Perm initially belonged to the same casual circle of friends as Ataru, with whom he shared an easygoing student life. The arrival of Lum changed the dynamic of this group. Perm and his companions reorganized themselves into her devoted protectors and admirers, and from that point their purpose was to guard Lum, win her love, and push aside anyone they saw as a rival for her attention. Their schemes rarely succeed, and they are frequently outmaneuvered or comically defeated. While the Stormtroopers themselves were developed for the original anime, Perm's real name and function connect him to Kousuke Shirai, a similar classmate in the original manga whose role the anime version absorbed.

Perm's personality is shaped largely by his infatuation with Lum. Like the other Stormtroopers, he can be obsessive in his devotion to her, and he often treats Ataru with hostility out of jealousy. Yet he is also an ordinary, youthful character who remains friendly with his comrades; the bond among the Stormtroopers does not stop them from competing with one another when they think a chance at Lum's attention is within reach. He calls Lum by the affectionate form Lum-chan, and during the middle stretch of the series he frequently joins forces with the wealthy student Mendo, another admirer of Lum, in attempts to get the better of Ataru.

His motivation is centered on winning Lum's affection and defending her from what the group views as threats, above all Ataru's wandering interest in other women. Although these efforts consistently end in failure, they drive much of his on-screen activity. In the overall story he functions as part of the recurring supporting cast of Ataru's classmates, appearing throughout the original television series and in its theatrical films and specials. His presence adds to the crowded, chaotic school life around the main characters and gives the series a regular group of hopeful, mostly unsuccessful suitors.

Among the Stormtroopers, Perm is notable for showing the most personal development. In particular, he is the only member of the group to be depicted with an actual girlfriend, a detail that sets him apart from his friends, whose lives remain almost entirely wrapped up in their admiration for Lum. This development suggests a gradual move beyond the single-minded devotion that defines the rest of the group.

Perm possesses no supernatural abilities and is an ordinary human student. His notable traits are physical and temperamental rather than magical: his tall, skinny frame, his permanently permed hair, and his enthusiastic, persistent pursuit of Lum. In the later anime adaptation of the series, the Stormtroopers as a group are not featured, though similar classmates based on the same character types do appear.