Herobrush

The Herobrush is a brush in Splatoon 2 that is exclusively used in Octo Canyon.

Description
The Herobrush has a very visually similar design to the Octobrush, but wears the usual black and lime-green color scheme of the Hero Weapons. It is usable in Octo Canyon and can be upgraded one level. Like all hero weapons in Splatoon 2, they come with switchable sub weapons of Splat Bombs, Curling Bombs and Autobombs. It is loaned by Sheldon during the level, Underground Expressway, and can be used in missions after beating the level. Beating all missions in Octo Canyon with it unlocks the Herobrush Replica for purchase at Ammo Knights.
 * At Level 1, the weapon has blue lights. It functions identically to the Octobrush.
 * At Level 2, the weapon has red lights. It has increased fling speed and power, and increased run speed while inking. The upgrade can be purchased at the Ammo Knights Enhancifier with 1,500 Power Eggs and three Sardinium.

Herobrush Replica
The Herobrush Replica is a reward in Splatoon 2 unlocked for purchase at Ammo Knights by beating all missions with the Herobrush. It is a brush-type main weapon and is visually identical to the Herobrush. Despite its unique appearance, it is simply a reskin of the Octobrush, sharing the same stats and loadout, Autobombs and the Inkjet.

Trivia

 * Unlike every other Hero weapon except the Hero Roller where the design and replica is based of the main weapon in it's class or sub-class, the Herobrush is based off the Octobrush and not the main weapon of the Brushes, the Inkbrush. This is presumably due to the fact the Octobrush is a more rounded weapon, with higher range and damage, and to provide a Hero centric counterpart to the Octarian based Octobrush. This may also be due to the fact that the Octobrush was released with launch of Splatoon 2 but the Inkbrush was not, although the fact that the Hero Brella Replica was based off the Splat Brella, which was also post-release content disputes this.