4-Koma

4-Koma (4コマ漫画 lit. four cell manga) also known as Yonkoma is a comic strip format. It consists of a story within 4 panels of equal size, thus the name. It has an order from top to bottom, and in the case of Saiki Kusuo no Ψ Nan, read from right to left. During the series' run, 4-Komas were made and published in different volumes of the manga series.

Extra
3 strips included in Volume 4, titled "Self Introductions" "Nendou Riki" and "Kaidou Shun."

2nd Extra
4 strips included in Volume 9, titled "Downsides to ESP (1-2)" and "The Strongest (1-2)." The strips were originally released on December 04, 2013 in Saikyō Jump.

The PSIadowy World of Kaidou Shun
7 strips included in Volume 19, titled "The Shadowy Secret Base" "3 Shadowy People" "A Shadowy Promise" "Shadowy Waiting" "A Shadowy Movie Theater" "Shadowy Clothes Store" and "A Shadowy Light in the Shadows."

Jump+ Anime Announcement
5 strips included in Volume 19. The first strip is the example image for the page and all 5 strips are available to read in Japanese for free on Shonen Jump Plus.

Summer Collection
9 strips included in Volume 23. Originally released on August 7, 2017 in Weekly Shōnen Jump. It is stories of the characters on summer vacation.

4-Koma Selection
17 strips included in Volume 26. Each strip was originally released weekly between March 5, 2018 to July 2, 2018 in Weekly Shōnen Jump a week after the release of Chapter 279. They are considered as a sequel to the series. However, only 2 strips references what happened in the world Kusuo erased and only 1 strip is a fully direct sequel, which was to promote Epilogue Chapter 1.