Kōsuke Shirai (白井 コースケ, Kōsuke Shirai?) is Ataru Moroboshi 's classmate and best friend, excluded from the Anime in favor of Lum's Stormtroopers.


Kōsuke is Ataru and Hokuto's best friend and the three of them are often seen causing trouble together. He has a girlfriend (who was willing to pose as "Shinobi Nobade" for him), and has received Valentine's Day chocolate from other girls, meaning he is somehow popular with girls. Like Shūtarō Mendō and the other male students, he is also in love with Lum and will try to prevent her from kissing Ataru, trying to protect her purity. In the later half of the series, he and Hokuto begin to become victims of the daily shenanigans. In the anime he only ever appears as a background character, and his roles are always given to either Megane or Perm.

He and Hokuto appear in the first chapter of the manga, but are replaced by Lum's Stormtroopers in Chapter 3. Kōsuke reappears shortly after Mendō debuts and quickly claims the position of main supporting character. In the anime, a lot of his major roles are taken by Megane, such as the Shinobi Nobade plot (renamed Kumino Otoko) and receiving a love letter from Lum in "Capture the Heart". In the final scene of Urusei Yatsura: The Final Chapter, Perm watches on in Kōsuke's place when Lum and Ataru embrace.

In "Farewell, Onsen-Mark", Onsen-Mark lists Ataru & Kōsuke as the two most dangerous students in the troublesome Class 2-4.

His handwriting is messy and he has poor writing skills, which Mendō frequently insults him for. However, his writing skills are good enough to trick Ataru in the Shinobi Nobade story.

Name Meaning

Kousuke's name comes from Shirai Kousuke (白井 康介, Shirai Kousuke?), an editor at Shogakukan at the time Urusei Yatsura was being serialized.


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