This is a prequel of mostly the 2nd year students but when they were first years.

yata Okkotsu is the main character here. He has a special grade vengeful spirit inside him named Rika. After she died at a young age she has haunted him. Though when he gets angry and she comes out, everyone should run, because she don't play. But when Gojo brings him under his wing with his other students he hopes to harness that power. Geto has other plans and launches a full on attack.

This is a pretty solid volume. If want some more background on characters, learn more about Yata who's pretty much gone in the main series training overseas, and learn more about Geto and Gojo, this is worth reading. The fights are fun, the stories are solid, pacing is really well done. Overall worth reading for sure if you're a fan of the main series.