Angry Grandpa

Angry Grandpa (マジギレ, Majigare) was a Mysterious Being that appeared in the audiobook, Sonic, Becoming Saitama. He was killed by Speed-o'-Sound Sonic.

Appearance
Angry Grandpa used to look like a regular human before transforming into a monster.

Personality
Angry Grandpa hated rowdy children. He would attack children for being rude. An example of this hatred is that he said: "I’m gonna teach all the kids around here a lesson in manners! And make sure none of them ever try to do whatever they want again like it’s a game!"

History
Pushed over the edge by screaming kids and loud music in public, Angry Grandpa became a monster.

Sonic, Becoming Saitama
Angry Grandpa fights Mumen Rider, but is eventually taken out by Speed-o'-Sound Sonic, who is disguised as Saitama.

Abilities and Powers
Angry Grandpa was able to put up a fight against Mumen Rider but was easily taken out by Speed-o'-Sound Sonic.

Physical Abilities
Enhanced Strength: Angry Grandpa was strong enough to punch holes in the ground.

Enhanced Durability: Angry Grandpa could withstand bullets from police-grade firearms to no apparent damage.

Frustration Accumulation: As Angry Grandpa accumulated frustration, he could unleash bursts of immense power.

Fighting Style
Hand-to-Hand Combatant: Angry Grandpa fought Mumen Rider in close quarters.
 * Furious Outburst Punch: The punch was strong enough to destroy concrete.

Trivia

 * Angry Grandpa was the only monster Speed-o'-Sound Sonic fought in order to save someone else.