A Late-Start Tamer's Laid-Back Life: Volume 10

As the second half of the summer event begins in full swing, Yuto finds himself facing down legions of the undead and a haunted sunken ship. When he finally learns about the raid boss that’s waiting for them at the end of the event, he decides to spread the information around as soon as possible so the players can have any hope of defeating it. Meanwhile, the devs are scrambling to keep up with the ever-changing demands of the event, as more and more players are rapidly progressing, deftly taking down dinosaur bosses, and finding rare items, all thanks to Yuto. But will all the players’ efforts be enough to handle what’s in store for the final day?

[From J-Novel Club]