Masafumi is Switch (Kazuyoshi)'s younger brother whose nickname is Switch in the Sket Dance franchise.
Masafumi Usui, who is created by Kenta Shinohara, has no information regarding any inspiration used to create him. He first appears in Sket Dance volume 5 and episode 24. His Japanese voice actor for his present self is Tetsuya Kakihara and for his younger self, it is Kaoru Mizuhara.
Like Sawa, Masafumi Usui does not change.
Like the future Kazuyoshi, Masafumi has glasses (real ones) and his attire is similar.
He is a happy brother who takes pride in his older brother. Like Kazuyoshi, he protects Sawa to the very end.
In the morning, Masafumi calls his big brother to wake up for school, and at breakfast, Kazuyoshi asks Masafumi to check his computer. Later on when Sawa and Kazuyoshi are in the bedroom, Masafumi arrives to find Sawa and compliments her on how her uniform makes her cute. He reveals his new software program to Sawa and Kazuyoshi, and he demonstrates how the software can sound out words by typing the characters. Sawa embraces Masafumi's back and tells him that she might marry him. Masafumi smiles at his older brother and thanks Kazuyoshi for teaching him about computers.
The following day, Masafumi finds out that Sawa has a stalker after her when she brings the stalker's letter to Kazuyoshi and him. When Sawa thinks of calling the police, Masafumi states that the police cannot help unless someone is injured; he tells her to buy something to protect herself. Then Sawa thinks about buying a stun gun, but Masafumi suggests a device that makes a loud alarm is more useful than a stun gun. Sawa compliments Masafumi, and as she is about to leave with Kazuyoshi, Kazuyoshi tells Masafumi to go shop with Sawa. When Kazuyoshi refuses to go with them, Sawa leaves with disappointment. Masafumi glances at his brother and tells him that he does not like Kazuyoshi this way. He reminds his brother of their childhood picture.
In the city, Masafumi and Sawa get lost when finding the shop. Masafumi reminds Sawa that Kazuyoshi has always looked after them. When Yukino finds them, it begins to rain. Yukino mutters that Sawa is on a date with her boyfriend, and as she walks towards them, she tells Sawa that she has nothing because her ex boyfriend is only interested in Sawa. Yukino lunges to stab Sawa, but Masafumi takes Yukino's attack to protect Sawa. Masafumi dies from his wound. His body is taken to his family, and his mother grieves with his father and brother. His body lays to rest, but only Kazuyoshi attends because Sawa has to stay in bed due to the shock.
Rest in Peace, Masafumi Usui.
Like Kazuyoshi, Masafumi created the speech software program. He's skilled at computer programming.