Aikurō Mikisugi

Aikurō Mikisugi (美木杉 愛九郎) is Ryūko and Mako's enigmatic homeroom teacher. Initially appearing dull and easily flustered, he secretly observes and aids Ryūko by leading her to Senketsu. It is later revealed he is working undercover at the school as a spy for the Nudist Beach rebel group.

Appearance
In his disguise, Aikurō looks like a middle-aged man with blue messy hair, with a bent back and an unsteady gait. His blue eyes are hidden behind large reflective glasses. When in his true persona, Aikurō removes the glasses and sweeps back his hair, revealing that he is actually a young and very handsome man. In both personas, he wears a white long-sleeved shirt with a black tie and black jeans, though in his true persona, the shirt is worn much more loosely as Aikurō has a tendency to strip his shirt off and show off his body like a posing supermodel. In this modeling mode, Aikurō sports sparkles all around him. Most notably, his nipples occasionally give off a pink glow.

Personality
Aikurō can easily be described as flamboyant and flirtatious, but can be serious and direct when he needs to. When undercover, he takes on the persona of a tired and unenthusiastic teacher. He is a glamorous smooth-talker with a habit of slowly stripping his clothes and making moves on Ryūko whenever they are in private, much to Ryūko's chagrin. Though he did reveal the existence of Nudist Beach and him being its agent to Ryūko, she did not believe him due to the organization's ridiculous name, earning a surprised and annoyed expression from the man, showing he takes great pride in the resistance group. Despite all of this, Aikurō cares for his students and often talked with Mako rather casually about the situation.

History
He once worked as an assistant to Ryūko’s late father, Isshin Matoi, whom was one of the few that knew of the potential of Life Fibers. After the death of Isshin, Aikurō received his letter that guided him to the whereabouts of the Kamui Senketsu, and the task to give Senketsu to his daughter.

To learn more about the Life Fibers, he infiltrated Honnōji Academy and went undercover as a high school teacher.

Relationships
Ryūko Matoi
 * While Ryūko does not yet seem to trust him completely, Aikurō seems determined to help her uncover the truth behind her father's murder. He is also constantly watching her fight from behind the scenes, always on high alert should something go wrong. He is shown to be especially concerned about Senketsu's fast evolution. When in Ryūko's presence, he has a tendency to show off his well built body. This flusters her and makes her uncomfortable. Aikuro has notably shown hesitation in any case of disposing of Ryūko as suggested by Tsumugu, even when Ryūko lost control and was consumed by her Kamui, hesitating in shooting her and alerting her berserked form to his presence.

Tsumugu Kinagase
 * Tsumugu and Aikuro are both members of Nudist Beach, created by Isshin Matoi as a rebel group against Life Fibers and COVERS. Tsumugu has previously stated that he owes Aikuro for an unspecified reason, and that he would follow any order of his except for when it comes to Kamuis, to which Aikuro both acts as if it is only a bother and warns him that those back at their Headquarters would confiscate his gear. Tsumugu and Aikuro both seem to place much trust in each other.

Memorable quotes
"Nudist Beach. We're Nudist Beach. It is the name of our organization. Nudist BEEEEAAAACH!"

- Aikurō stylishly reveals the name of his rebel group

"Come with me. I gave you my word. It's time to tell you everything."

- When Ryūko proves herself to be a valuable ally, Aikurō fulfills his promise

"I'm going to use the Naked Sun's final trump card: the Great Naked Blade!"

- When Aikurō decides to use the Naked Sun to destroy the Original Life Fiber

"Today, I return to my unadorned self! As one of the unclothed warriors of Nudist Beach who do battle against the threat of Life Fibers: a Nudist Beach Splendid Naked Officer, Aikurō Mikisugi! Let's begin!"

- Aikurō decides to abandon Honnōji Academy and reveals himself as a Nudist Beach operative.

Trivia

 * He also owns a car named Naked Shooting Star (裸の流星号).
 * He bears a slight resemblance to Kamina from fellow Trigger anime, Tengen Toppa Gurren Lagann.
 * Aikuro has the same voice actor as Kisuke Urahara from Bleach.
 * His trademark mirrored sunglasses reflect the same image no matter where he looks, that of an upside down flat horizon, with the ground up top and the sky in the lower half.
 * He has a running gag that whenever he strips, or is in his Nudist Uniform, his nipples and crotch area start glowing a bright pink purple.
 * Aikurō's theme song is contained in the 3rd track of the Kill la Kill OST, 犬Kあ3l (いぬかさる), which also contains the themes for Hōka Inumuta and Uzu Sanageyama.
 * Aikurō has another recurring gag, his hate of the name "Dōtonbori Robo". Whenever the name is mentioned, it is shown a close-up of him making a serious face and saying "DTR" twice.