Water Gun

Water Gun is a C-class hero for the Hero Association.

Super Fight Arc
He is encountered by Saitama and tells him that he was defeated and that the monsters had left 30 minutes prior.

Abilities
As a C-class hero, it can be assumed that Water Gun isn't a very powerful individual. Since his rank is unknown, it is unknown how he compares to other heroes in his class.

Equipment
Water Gun: His titular weapon. Like you would expect, it makes him effective against fires and fire-based monsters.