To access the content of a .tar.zst file, you will need a modern extraction tool, as older versions of standard software might not support the Zstd compression:
If you are looking for a place to read this legally, Oshioki Execute is a series often found through official digital manga platforms or tankōbon (collected volume) retailers in Japan. To access the content of a
.tar is an archive format used to group multiple files together. To access the content of a
This indicates the collection includes all 5 volumes of the series. To access the content of a