Delusional Protagonist

A visual novel with this tag has a protagonist (or multiple) that are delusional.

A delusion is a belief held with strong conviction despite superior evidence to the contrary. Unlike hallucinations, delusions are always pathological (the result of an illness or illness process). As a pathology, it is distinct from a belief based on false or incomplete information, confabulation, dogma, illusion, or other effects of perception.