|Japanese Name:||笹原 幸治郎|
|Romanized Name:||Sasahara Kōjirō|
|English Name:||Koujirou Sasahara|
|First Appearance:||"Nichijou Episode 1"|
|Affiliated:|| Misato Tachibana (friend)|
|Japanese VA:||Yoshihisa Kawahara|
|English VA:||Seth Magill|
Koujirou Sasahara is a flamboyant high school boy who likes to think he is an aristocrat, when in reality his family are just farmers. He likes to ride his goat to school and is often seen with his butler. Misato Tachibana has a crush on him but shoots him with various heavy weapons to hide it when she feels embarrassed about it.
Koujirou wears glasses, and is often seen wearing a male high school uniform with a jabot (actually made of tissues). He doesn't actually need to wear glasses and only wears them for show.
Koujirou behaves much like an aristocrat. He is almost always calm and collected, and very rarely, if ever, gets visibly angry. He can be rude to others at times, but he can also be kind and gentlemanly, such as when he handed a piece of his collar to Misato Tachibana to wrap around her hand when she accidentally smashed his glasses. Adding to his aristocratic air is his insistence that he ought to ride a goat to school, to avoid walking.
He always refers to Misato by her full name. He doesn't seem to care that Misato often shoots him with various weapons, and always appears unfazed no matter how many times he is shot. He is seemingly oblivious to her crush on him as well.
Mio has a crush on Koujirou, though he doesn't seem to be aware of her due to her shyness around him.
Misato also has a crush on Koujirou but has a very tsundere attitude towards him. This causes her to frequently injure him through fake firearms, though he never pays any mind to these instances. It is said that they are childhood friends and attended Kendo classes together; Misato gets frustrated that he doesn't work hard enough at Kendo, and does not tolerate his aristocratic nature or gestures.
Hirose is a Koujirou's butler. He always go with Koujirou Wherever he goes, though why he does so when Koujirou is not actually an aristocrat goes unexplained.
Yoshino had previously practiced kendo with Koujirou.
- It is revealed in episode 2 that he is the president of the Drama Club.
- Like Mai Minakami, Koujirou is often seen engaging in non-sequitor behavior, such as randomly playing a Game Boy or reading a novel during conversation. Unlike Mai, this appears to be less about teasing others and more his natural behavior.
- Mio typically uses Koujirou as the subject of her self-published yaoi manga.