The mural "Watcher," also known as Mr. Periscope, is located on the side wall of an apartment building at 73 Gliwicka Street in the Załęże district of Katowice. It was created in April 2024 and is one of the largest works by Noriaki – a street artist from Poznań who remains anonymous.

The work depicts a distinctive, minimalist figure with one large eye, serving as the author's alter ego. Watcher serves as an independent observer of urban space, and its simple, comic form is meant to engage with passersby and symbolically "wink" at them. In the Katowice version, the figure holds a spray paint can, which emphasises its street art character.

The mural was created as part of the "Within the City: Urban Art" project, conceived and curated by Krzysztof Krot. Noriaki carried out the project independently, first thoroughly analysing the dimensions and structure of the facade to integrate the geometric figure into the architecture of the tenement house. The motif of Mr. Periscope, initially associated mainly with Poznań, can now be found in many cities around the world.