Volume 20 of Jujutsu Kaisen (呪術廻戦) a manga series written and illustrated by Gege Akutami. It was first published in March of 2018 in Shonen Jump Magazine.
This limited edition includes a box with 20 official pins with the characters of the series.
The plot follows Yuuji Itadori, a teenager who joins the occultism club at school. However, one day he will see an evil spirit who threatens peace and stability, so Yuuji must become a sorcerer to fight against him.