Saitama vs. Cruel Dragon

The time has finally come... The hatred I have accumulated over the years... will be repaid with the lives of all humanity.'''

Saitama vs. Cruel Dragon is the battle between Saitama and Cruel Dragon.

Prelude
Saitama accidentally gets into a conflict between two groups known as the Saints and Deathbone that have been fighting for the last 800 years over nine stones that were used to seal Cruel Dragon, an ancient creature that once wreaked havoc on humanity before being sealed a long time ago. While the Saints wishes to keep the dragon sealed to maintain world peace, Deathbone thirsts for the dragon's resurrection and humanity's destruction. Saitama decides to release Cruel Dragon from its seal in order to eliminate it and end the conflict between the two parties that has lasted 800 years. After Saitama soon collects the nine stones that were used to seal the dragon, a summoning ceremony is performed by a member of Deathbone. Cruel Dragon is subsequently released from its seal after centuries of imprisonment.

Battle
Upon being unsealed, Cruel Dragon announces its intentions to destroy humanity before breathing a fire blast towards Saitama. The fight is over in an instant when Saitama counters with a single punch that blows Cruel Dragon into pieces.

Aftermath
After the battle, Saitama heads back to his apartment and plays video games with King. He tells King that he did not think cults and seal stones actually existed and that there are many things in the world he still does not know of.