|Kazuyoshi Usui / Switch|
|Birthday||February 28, 1993|
|School||Kaimei High School|
2-C (chapters 1-209)
3-C (chapters 210-288)
|Likes||Science, modern-day pop culture|
|Dislikes||Carbonated drinks, the occult|
Masafumi Usui (brother, deceased)
|Manga Debut||Chapter 1|
|Anime Debut||Episode 1|
Aki Kanada (young)
Kazuyoshi Usui (笛吹 和義), or Switch (スイッチ), as he is more commonly called, is the brains of the Sket Dan. As a result of the events that happened in his life, he opts to speak through a voice synthesizer on his computer.
Kazuyoshi and his brother Masafumi, who was only a year younger, had grown up alongside their childhood friend Sawa. In his freshman year of high school, Kazuyoshi really started to feel the difference between his brother's scientific intellect and electronics skills and his own. When Sawa received a death threat in the mail after having been plagued by a stalker, she turned to the brothers for advice and Kazuyoshi ended up frustrated that Masafumi's knowledge undermined his own suggestions. Coming to the conclusion that he would never be able to protect her, and that his brother was better than him where it counted, he refused to accompany Sawa in buying self-protection equipment. His explosion resulted in Masafumi accompanying her instead, while Kazuyoshi mused in his room.
While the two were out, Sawa's friend Yukino stopped by and told Kazuyoshi what she had learned about the boy stalking Sawa. Evidently, he had stabbed a classmate back in middle school and still carried a knife with him wherever he went. Kazuyoshi called his brother to inform and warn him and Sawa of the potential threat, and when Yukino voiced her surprise at Sawa's companion, Kazuyoshi stated that it was Masafumi and Sawa who were dating, not him. As he was turning to go, Yukino spotted Sawa's stalker and Kazuyoshi proceeded to chase him down. The boy, Shinji, ended up simply being an anxious admirer with a crush - but from him, Kazuyoshi learned the truth behind the middle school stabbing story. The one who had really stabbed a student had been Yukino, who could grow violent when begrudged. As she and Shinji had been dating before he fell for Sawa, Kazuyoshi realized who Yukino was targeting and hurried to join his brother and friend.
However, he arrived at the scene only to find his brother being wheeled into an ambulance, and ultimately dying as a result of a stab wound to the chest, particularly near the heart (in the anime, he was stabbed at the back). Once Kazuyoshi learned that Yukino had stabbed Masafumi because of a mistaken belief that he was Sawa's boyfriend, he blamed himself entirely for his brother's death. He despaired, not understanding how he could be alive when his brother, who had had all the potential and talent, was dead. So he cut his hair, styled it like his brother's and started wearing his brother's old glasses with the lenses removed out of a desperate need for some trace of Masafumi to remain in the world.
When he returned to school, Kazuyoshi wanted people to call him "Switch" - his brother's old nickname, and after a while he stopped attending upon thinking how pointless his routine had become. Withdrawing into himself, he stopped talking and became a hikikomori. It was Bossun who drew him out of his misery and put him back on his feet.
Prior to Masafumi's death, Switch has slightly longer and messier hairstyle, and he did not wear glasses. Aside from his uniform, his home clothes are less casual than his present attire.
He is noted to be very handsome. Along with his odd manner of speaking (through the voice synthesis program on his laptop), Switch is very popular for being both mysterious and good looking. His current appearance is intended to copy that of his deceased brother. For his outfit, he usually wears a green vest over his uniform, and his glasses have plastic frames.
Switch grows his hair out. 
In a past, he was quite laid back and devoted to protecting Sawa and his younger brother. He's calm and a perfect figure of an older brother for Masafumi. Switch began to envy Masafumi as he created something by himself and impressed Sawa. After the death of his brother, he tried to come to school but he felt hurt, so his homeroom teacher told him to not come to school when he doesn't feel strong enough.
After recovered from shut-in problems due to his dark past and prior graduating high school, he is calm, reserved, and stoic, rarely showing any emotion. He has a deadpan sense of humor and seems to enjoy teasing others. Because he always communicates through speech synthesis software and has a tendency to joke with a straight face, it is difficult to tell what he is really thinking. While he usually "speaks" without much emotion, he would sometimes purposely raise his "voice" to abnormally high levels for comic relief. He often becomes very passionate about anime and often provides a very detailed and hilariously in depth commentary on the various animes featured in the series.
At the end of the series, he is finally fully recovered.
Major Story Points
Gachinko Vivage Battle
Switch and the Sket Dan enter the tournament to win an app for Moe, a "3" lip. They have to face off with the Student Council. After Himeko and Shinzō's valiant efforts, Switch confronts Daisy in a shoot-off. Before the match begins, Switch attempts to taunt Daisy only to receive verbal abuse from Daisy. With only six shots and armed with 2 infrared handguns, the two students have to score three hits on their opponents to win. While Switch misses his first shot, Daisy has score two shots successively. Switch fires multiple times at Daisy until he scores one hit. Then, he tricks Daisy by using his laptop to sound off a gun shot which allows him to score another hit on Daisy.
In a standoff, Daisy's insults cause Switch to miss his shot. Quickly, Daisy draws her second gun. Before Daisy shoots, Switch throws his empty gun at Daisy. Both opponents shoot at each other. The game ends with Switch's victory. When Daisy asked how Switch was able to shoot without switching his gun to his right hand, Switch replies that he is ambidextrous. 
Defeat the Fortune Teller
After Himeko brings up Himiko Minakami's divination, Switch points out why Himiko and her fortune telling is a fraud. When Himeko leaves to see Reiko and get her fortune read, Bossun and Switch follow Himeko out of concern. Over at the Occult Club, Switch quickly takes Himeko's place and asks Reiko to read his fortune. Switch and his friends are alarmed when Reiko suggests that Switch should buy a charm to protect him. Concerned that Reiko is caught up in a scam, Bossun and the gang request Reiko to arrange a meeting with Himiko. At Himiko's office, Switch conveys his opinions about her fortune-telling. Irritated by Switch, She challenges Bossun and the others to prove who's wrong at her seminar three days from now.
At their way back home, Switch assures Bossun that he has a plan. Three days later, while everyone gets settled at the seminar, Switch starts hammering his arguments about why Himiko's fortune telling is a scam. Then, Himiko has Bossun come up, so she can read his past life. Though, she is tricked when the person she interviewed was Tsubaki in disguise. After Himiko is exposed in front of her believers, Reiko thanks them for opening her eyes. Switch gives her an advice; thus, starting another argument between old friends. 
For finding the identity of the Kaimei Hidden Website admin, Bossun tries to contact Switch via Virtualand, an online social game to ask for advice. When Bossun tells him that he's first year in Kaimei, Switch runs away from Bossun but when Bossun says he only needs his help, he decides to hear Bossun story.
After some observation Bossun sends a message to Switch's phone, asking if Switch is the website admin which Switch replies 'yes'. Bossun then tells him to meet in Virtualand after that. In Virtualand, Switch asks Bossun how did he figure out his identity and Bossun gives his theories. Bossun asks why did Switch do such a thing, and Switch replies that 'bad guys need to be punished' and signs off after saying that he will never speak again.
One day, Switch receive a message from Okuyama and soon gets called by him. Okuyama states that he's in his way to Switch's house with the losers of Death Match to 'meet' him. In the middle of the call there's another someone's voice that is trying to stop Okuyama and Switch wonders whose voice was it. Just a few hours later Bossun comes with battered face with Himeko and talks to Switch. Switch replies using synthetized voice from his laptop and says that his heart hurts too much. After some pause Himeko shatters Switch bedroom window and Bossun comes inside, just to immediately punches Switch.
After some time fighting, the trio worked together for the first time. After that Switch promises that he will soon make his step to outside but stating that he still needs some time to do it. A few days later, Switch comes to school and is warmly welcomed by everyone. He then meets up with Bossun and Himeko to sign their club. After signing they're deciding their nickname, and Switch tells the two that he wants to be called Switch, his late brother's nickname. 
- Electronic Master: With his laptop, he is shown to do multiple things in an easy way and in swift motion like the following:
- Tone Changer: Switch is shown to be able to change the tone of the voice in his speech synthesis software into different tones he likes. There are multiple times he uses this, and he sometimes uses it to his advantage and uses it for mimicry.
- Database of Information: He is known to have lots of information throughout the whole school and those who are in it. He knows exactly what Hime’s full name, height and weight to her frustration. He also has lots of information of anime and manga’s, though he denies of being an ‘otaku’.
- Skilled Inventor: He has a large talent for ‘crazy’ inventions, though his obsession for this has rooted from the death of his younger brother, though even before, he still knows how to create inventions.
- Yuusuke "Bossun" Fujisaki: Much like Himeko, Switch feels that he owes Bossun a great debt for having saved him. Despite his quirks, he is just as loyal to Bossun as she is. Though Bossun is not a heavy otaku like Switch, they often talking about tonkusatsu and lend anime DVDs to each other.
- Masafumi Usui: Masafumi was Switch's younger brother and the original 'Switch'. Switch (Kazuyoshi) introduced Masafumi to the computer and soon Masafumi surpassed him, catching the attention of their childhood friend, Sawa. Switch had feelings for Sawa but in other hand, he also admired Masafumi. After Masafumi's death from a tragic accident, Switch blamed himself and became withdrawn, changed his appearance to look like Masafumi and refused to speak, a tribute to his brother.
- Sawa Yamauchi: Sawa is Switch and Masafumi (former Switch)'s childhood friends. Before moving out, Switch tells her that he loved her and she replies "me too".
- Momoka Kibitsu: Momoka is hinted to have feelings for Switch. When Momoka asks Switch why he has visited all of her concerts, Switch replies via sketchbook to support her. Momoka thinks it a lie. On Valentine's Day, Momoka gives Switch a honmei choco . She thanks him for always supporting her, but he points out that all of her fans have supported her, too. She asks if Switch likes anyone or has any interest in getting a girlfriend but he answers that he will never fall in love again as he recalls his final goodbye with Sawa. After fully recovered from the past he was haunted by, and after graduation from high school, Switch decide to keep moving forward and accept Momoka's feeling as they starting on a date afterwards.
- Reiko Yuuki: Reiko and Switch are rivals. Reiko is an occult believer, contradicting Switch's belief in science. Reiko often visits Sket-dan to challenge Switch even though she often gets proven wrong. Switch seems to be unfrightened by Reiko's screaming and creepy antics. However, Switch does help her, like making her beautiful in front of the guy she once had a crush on and give Reiko the proof about the fortune teller's tricks
- In the original oneshot, his first name was written as "一義," whereas it was changed to "和義" for the serialization. Both are read as "Kazuyoshi," however. Shinohara stated that originally, Switch was named after the musician Kazuyoshi Nakamura (中村 一義). After the change in kanji, he then made reference to also liking the musician Kazuyoshi Saito (斉藤 和義).
- In the manga, Switch says his favorite Arrancar from the manga Bleach is Aaroniero Arruruerie. In the anime, this line is changed to his favorite Visored being Kensei Muguruma.  This is likely due to the fact that his voice actor, Tomokazu Sugita, also voices Kensei.
- Switch's first encounter with Bossun was an accidental collision in the school hallway, prior to the start of his backstory. Additionally, his backstory takes place during the spring and summer of the first year of high school. 
- Switch's laptop voice is a mixture of his deceased brother's and his voice.
- "The wind blowing in through the window made me uncomfortable. So I closed the window. I... stopped talking. As for when that window was wrenched open... and a hand appeared through it, pulling me back up onto my feet... That wasn't until, a little later."