loyal customer; frequent visitor
Wasei-eigo from English 'heavy repeater'; used in business and casual contexts for someone who repeatedly uses a service or visits a place.
wasei-eigo (Japanese-coined English), from heavy repeater
That café has many loyal customers.
He is a frequent visitor to this site.
Variant with interpunct; less common but still seen.
Wasei-eigo from English 'heavy repeater', combining 'heavy' (frequent) and 'repeater' (someone who repeats). The English phrase is not used in the same way.