Energiser

Energiser (エナージラ, Enājira) is a Mysterious Being located in the uninhabited area in Z-City in the audiobook, "Sonic, Becoming Saitama". It was killed by Saitama.

Personality
Energiser was confident in its abilities but was still cautious. It recognized that there were beings stronger than itself and would go into hiding to avoid attention.

History
Energiser was a powerful monster hiding in Z-City’s uninhabited zone. It was discovered by the Hero Association and was targeted for attack.

Sonic, becoming Saitama
Tornado of Terror and Atomic Samurai are tasked to eliminate Energiser, but Speed-o'-Sound Sonic, disguised as Saitama, encounters the monster first. Sonic struggles to fight Energiser. Fortunately for Sonic, the real Saitama arrived and together they easily defeated the monster.

Abilities and Powers
As a Dragon-level Mysterious Being, Energiser was very powerful. It fought Speed-o'-Sound Sonic and would have killed the ninja had Saitama not intervened.

Physical Abilities
Immense Durability: Energiser took several of Speed-o'-Sound Sonic's shurikens without any significant damage.

Supernatural Abilities
Energy Projection: Energiser has the ability to compress and emit energy from its hands. It has a limitless energy stock, but it needs time to build energy blasts up.