One Punch Man, Vol. 6

One. One Punch Man, Vol. 6. 216. 207p. ISBN 9781421585277. 

All Class S heroes were summoned to gather at City A's heroes headquarters in One Punch Man, Vol. 5. The death of the seer following her prediction that a catastrophe was threatening Earth forces the Heroes Association to begin planning. The problem is that no time frame was provided for this danger, so it could be next week, or in six months. However, every prediction ever made by the seer became true, so the danger is real. 

The other Class S heroes are wondering why Saitama, a Class B hero, is also present at the meeting, but before they are able to kick him out City A is attacked from the air by a large spaceship, and a monstrous being begins rampaging on the ground. Saitama immediately flies out of the building and boards the ship. The other heroes, unable to reach the ship, attack the monster, but it is proving impossible to defeat.

As bombs rain from the sky and destruction is delivered to the city, Saitama searches the ship for its master, while Genos and the other heroes struggle. Will this be the end of the Heroes' Association?

The story continues in One Punch Man, Vol. 7.